Wireless terminal, wireless base station, and transmission method of buffer status report

ABSTRACT

A wireless terminal for a wireless communication, the wireless terminal includes: a memory that includes a buffer configured to store uplink data, wherein the uplink data is configured to be transmitted; and a controller configured to transmit a buffer status report, the buffer status report including a first index, wherein the first index is one of a plurality of buffer status indices and corresponds to a buffer size indicating a size of the uplink data stored in the buffer, wherein the memory is configured to store a buffer status table in which a range from a minimum value of the buffer to a maximum value of the buffer is divided into a plurality of subranges, the plurality of subranges being associated with a part of the plurality of buffer status indices, and a rest of the plurality of buffer status indices are associated with one or more reserved fields.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of InternationalApplication PCT/JP2017/040996 filed on Nov. 14, 2017 and designated theU.S., the entire contents of which are incorporated herein by reference.

FIELD

The present invention relates to a wireless terminal, a wireless basestation, and a transmission method of a buffer status report.

BACKGROUND

In recent years, in a wireless communication system (also referred to asa mobile communication system) such as a portable phone system (cellularsystem), the next generation wireless communication technology has beendiscussed in order to more increase the speed and the capacity ofwireless communication. For example, in the 3rd generation partnershipproject (3GPP) being a standard organization, developing specificationsof the communication standard referred to as long-term evolution (LTE)or the communication standard referred to as LTE-Advanced (LTE-A) whichhas been based on the wireless communication technology of LTE has beenalready performed. In addition, studying enhancement of the function hasbeen continuously carried out. For example, the discussion aboutstandardization of the fifth-generation mobile communication system(also referred to as a 5G system) that realizes the contents of anoperational scenario and technical requirements presented from theinternational telecommunication union radio communication sector (ITU-R)has been carried out.

In the wireless communication system as described above, a wirelessterminal transmits uplink (also referred to as a UL) schedulinginformation, for example, a buffer status report (also referred to as aBSR) of the wireless terminal (also referred to as a terminal, a userterminal, or a mobile station), to a wireless base station such that thewireless terminal is capable of assisting that a wireless base station(also referred to as a base station) performs scheduling of wirelessresources with higher efficiency. Regarding transmission of a bufferstatus report (BSR) of the wireless terminal, for example, informationis transmitted based on the volume of data stored in a transmissionbuffer of the wireless terminal.

From a viewpoint of transmission efficiency of the BSR, the wirelessterminal performs compression of information volume by converting thevolume of data stored in the transmission buffer (also referred to as abuffer) into an index value (also referred to as a BSR index). The indexvalue is obtained by quantizing the volume of the data in apredetermined granularity. Therefore, a buffer status report index table(also referred to as a BSR index table) is provided in the wirelessterminal and the wireless base station. In the BSR index table, a rangefrom the minimum value of the BSR to the maximum value thereof (forexample, a range from 0 bytes to 150000 bytes) is divided into aplurality of subranges, and the index value of each subrange correspondsto a range of a data volume (also referred to as a buffer value or abuffer size) in the buffer. Any one (for example, the last BSR index) ofa plurality of BSR indices in the BSR index table is correlated with astate where the buffer value exceeds the maximum value.

The wireless terminal identifies an index value (also referred to as aBSR index, a BSR index value, or a BSR value) associated with a subrangecorresponding to a data volume (also referred to as a buffer value, abuffer size, or data available for transmission) in the buffer, inaccordance with the above-described BSR index table. The wirelessterminal transmits a BSR including the identified BSR index. Thewireless base station receives a BSR from the wireless terminal, andthus may recognize the amount of wireless resources that a wirelessterminal needs to be allocated, and is able to perform suitablescheduling. The wireless terminal may actively request allocation ofwireless resources from the wireless base station.

The transmission of the BSR from the wireless terminal is triggered inaccordance with a period designated by setting information transmittedfrom the wireless base station, for example. The wireless base stationestimates a buffer size of the wireless terminal based on the BSR fromthe wireless terminal and updates the estimated value of the buffer sizeof the wireless terminal based on, for example, the amount of wirelessresources allocated in scheduling. The BSR may be transmitted from thewireless terminal by a trigger other than the period designated bysetting information transmitted from the wireless base station. Forexample, it is assumed that the wireless terminal transmits a BSR to thewireless base station when a packet of an uplink signal is generated, orin a case where the number of padding bits included in the packet isequal to or greater than a predetermined value.

Examples of the related art include PTL 1: Japanese Laid-open PatentPublication No. 2016-181925, NPL 1: 3GPP TS36.211 V14.3.0 (2017-06), NPL2: 3GPP TS36.212 V14.3.0 (2017-06), NPL 3: 3GPP TS36.213 V14.3.0(2017-06), NPL 4: 3GPP TS36.214 V14.2.0 (2017-03), NPL 5: 3GPP TS36.300V14.3.0 (2017-06), NPL 6: 3GPP TS36.321 V14.3.0 (2017-06), NPL 7: 3GPPTS36.322 V14.0.0 (2017-03), NPL 8: 3GPP TS36.323 V14.3.0 (2017-06), NPL9: 3GPP TS36.331 V14.3.0 (2017-06), NPL 10: 3GPP TS36.413 V14.3.0(2017-06), NPL 11: 3GPP TS36.423 V14.3.0 (2017-06), NPL 12: 3GPPTS37.324 V0.2.0 (2017-09), NPL 13: 3GPP TS37.340 V1.0.0 (2017-09), NPL14: 3GPP TS36.425 V14.0.0 (2017-03), NPL 15: 3GPP TS38.201 V1.0.0(2017-09), NPL 16: 3GPP TS38.202 V1.0.0 (2017-09), NPL 17: 3GPP TS38.211V1.0.0 (2017-09), NPL 18: 3GPP TS38.212 V1.0.0 (2017-09), NPL 19: 3GPPTS38.213 V1.0.0 (2017-09), NPL 20: 3GPP TS38.214 V1.0.0 (2017-09), NPL21: 3GPP TS38.215 V1.0.0 (2017-09), NPL 22: 3GPP TS38.300 V1.0.0(2017-09), NPL 23: 3GPP TS38.321 V1.0.0 (2017-09), NPL 24: 3GPP TS38.322V1.0.0 (2017-09), NPL 25: 3GPP TS38.323 V0.3.0 (2017-08), NPL 26: 3GPPTS38.331 V0.0.5 (2017-08), NPL 27: 3GPP TS38.401 V0.2.0 (2017-07), NPL28: 3GPP TS38.410 V0.4.0 (2017-09), NPL 29: 3GPP TS38.413 V0.3.0(2017-08), NPL 30: 3GPP TS38.420 V0.2.0 (2017-07), NPL 31: 3GPP TS38.423V0.2.0 (2017-06), NPL 32: 3GPP TS38.470 V0.3.0 (2017-09), NPL 33: 3GPPTS38.473 V0.3.0 (2017-09), NPL 34: 3GPP TR38.801 V14.0.0 (2017-03), NPL35: 3GPP TR38.802 V14.1.0 (2017-06), NPL 36: 3GPP TR38.803 V14.1.0(2017-06), NPL 37: 3GPP TR38.804 V14.0.0 (2017-03), NPL 38: 3GPPTR38.900 V14.3.1 (2017-07), NPL 39: 3GPP TR38.912 V14.0.0 (2017-03), NPL40: 3GPP TR38.913 V14.3.0 (2017-06).

SUMMARY

According to an aspect of the disclosure, a wireless terminal for awireless communication, the wireless terminal includes: a memory thatincludes a buffer configured to store uplink data, wherein the uplinkdata is configured to be transmitted; and a controller configured totransmit a buffer status report, the buffer status report including afirst index, wherein the first index is one of a plurality of bufferstatus indices and corresponds to a buffer size indicating a size of theuplink data stored in the buffer, wherein the memory is configured tostore a buffer status table in which a range from a minimum value of thebuffer to a maximum value of the buffer is divided into a plurality ofsubranges, the plurality of subranges being associated with a part ofthe plurality of buffer status indices, and a rest of the plurality ofbuffer status indices are associated with one or more reserved fields.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an example of a sequence of BSRtransmission in a wireless communication system according to Example 1.

FIG. 2 is a diagram illustrating an example of a BSR index tableaccording to Example 1.

FIG. 3 is a diagram illustrating an example of a buffer status reportaccording to Example 1.

FIG. 4 is a diagram illustrating an example of a flow of processing of awireless terminal in a BSR transmission sequence according to Example 1.

FIG. 5 is a diagram illustrating a flow of processing of a wireless basestation 20 in the BSR transmission sequence according to Example 1.

FIG. 6 is a diagram illustrating an example of a BSR index tableaccording to Example 2.

FIG. 7 is a diagram illustrating an example of a buffer status reportaccording to Example 2.

FIG. 8 is a diagram illustrating an example of a flow of processing of awireless terminal 10 in a BSR transmission sequence according to Example2.

FIG. 9 is a diagram illustrating a flow of processing of a wireless basestation 20 in the BSR transmission sequence according to Example 2.

FIG. 10 is a diagram illustrating an example of a BSR index tableaccording to Example 3.

FIG. 11 is a diagram illustrating an example of a flow of processing ofa wireless terminal 10 in a BSR transmission sequence according toExample 3.

FIG. 12 is a diagram illustrating an example of setting informationregarding a correspondence relation between a conversion table and a LCGaccording to Example 3.

FIG. 13 is a diagram illustrating a flow of processing of a wirelessbase station 20 in the BSR transmission sequence according to Example 3.

FIG. 14 illustrates a content example of the BSR index table in a casewhere the BSR index is extended to 8 bits.

FIG. 15 is a diagram illustrating a content example of a BSR index tableaccording to Example 4.

FIG. 16 is a diagram illustrating an example of a hardware configurationof the wireless terminal 10 and the wireless base station 20 in awireless communication system 1.

DESCRIPTION OF EMBODIMENTS

In the next generation mobile communication system subsequent to thefifth-generation mobile communication system, for example, providing aservice such as a tactile communication and augmented reality, whichdesires transmission of a super high speed and large capacity which arehigher than the levels in the related art is expected. For realizingsuch a service, in the fifth-generation mobile communication system, anenhanced mobile broadband (eMBB) being a super high speed and largecapacity transmission service is set as one of functional requirements.For example, in the fifth-generation mobile communication system, it isaimed that a communication speed exceeding 10 Gbps (10×10{circumflexover ( )}12 bps) and large capacity as much as about 1000 times capacityin the fourth-generation mobile communication system (may also bereferred to as LTE) are realized.

However, the discussion in the fifth-generation mobile communicationsystem is just started. Thus, it is considered that the basic systemdesign is mainly discussed for now. Therefore, a technology which isproperly implemented in an operator has not sufficiently examined yet.For example, discussion about the issue of BSR implementation inrealizing eMBB has not progressed much.

Considering the above-described circumstances, an object of thetechnology in the disclosure is to provide a wireless terminal, awireless base station, a wireless communication system, and atransmission method of a buffer status report (BSR), in which it ispossible to solve the issue of BSR implementation in thefifth-generation mobile communication system.

Example 1

Hereinafter, examples of a wireless terminal, a wireless base station, awireless communication system, and a wireless communication methoddisclosed in this application will be described in detail with referenceto the drawings. The examples which will be described below are notlimited to the technology in the disclosure. The examples which will bedescribed below may be appropriately combined and conducted. Here,details of all NPL 1 to NPL 40 are incorporated herein by reference.

As described above, the discussion in the fifth-generation mobilecommunication system is just started. Therefore, for example, discussionabout the issue of BSR implementation which may occur in realizingenhanced mobile broadband (eMBB), has not progressed much.

The inventors of the present invention independently examined problemsin implementation which might occur in realizing the fifth-generationmobile communication system. As a result, the inventors found that, inan aspect of the fifth-generation mobile communication system, thefrequency of generating uplink data might be significantly increased ina wireless terminal (may also be referred to as a terminal, a userterminal, or user equipment) in which using a super high speed and largecapacity transmission service was supposed, by significantly improving adata transmission rate in comparison to that in the related art. Forexample, it may be supposed that pieces of data from various devicessuch as sensors, which are associated with the wireless terminal arefrequently generated and stored in a transmission buffer. However,uplink data is stored in the transmission buffer of the wirelessterminal until a timing at which uplink wireless resources are allocatedarrives. Thus, the volume of uplink data (may also be referred to as abuffer value, a buffer size, data available for transmission, or datavolume) which is stored in the transmission buffer of the wirelessterminal and is not transmitted yet may significantly increase. Thebuffered volume may be reduced by the uplink data being transmitted inaccordance with the timing at which the uplink wireless resources areallocated.

In this manner, in the aspect of the fifth-generation mobilecommunication system, the volume of uplink data (may also be referred toas a buffer value, a buffer size, data available for transmission, ordata volume) stored in the transmission buffer of the wireless terminalmay increase or decrease rapidly. Therefore, if the granularity ofbuffer values correlated with index values (may also be referred to asBSR indices) defined in a BSR index table is set as roughly as that inthe fourth-generation mobile communication system, a circumstance inwhich accuracy of the estimated value (may also be referred to as abuffer estimation value) of the buffer size of the wireless terminal inthe wireless base station (may also be referred to as a base station ora gNB below) decreases may occur. In other words, a difference between abuffer estimation value in the wireless base station and the actualbuffer size in the wireless terminal becomes greater, and thus it isdifficult to realize the best uplink scheduling.

For example, in the fourth-generation mobile communication system, abuffer value in a range from 0 bytes to 150000 bytes (=150 KBytes) isexpressed at 63 steps with the first to 63th BSR indices of a 6-bit BSRindex (that is, 2{circumflex over ( )}6=64 BSR indices) (for example,see 3GPP TS36.321 V14.3.0-Table 6.1.3.1-10). The last BSR index (thatis, the 64th BSR index) indicates a buffer value exceeding 150000 bytesas the maximum value of the above-described range. If the BSR indexhaving such a granularity is applied even in the fifth-generation mobilecommunication system, the buffer value of the wireless terminal easilyexceeds 150000 bytes as the maximum value by using the enhanced mobilebroadband (eMBB), for example. As a result, in a buffer status report,the 64th BSR index is often used.

However, the 64th BSR index of “63” in the related art only indicatesthat a buffer value BS exceeds the maximum value (150000 bytes) of abuffer, which is defined in a BSR index table, and there is nothing todo with indicating the extent to which the degree of the buffer valueexceeds the maximum value. Therefore, accuracy of the buffer estimationvalue in the wireless base station greatly decreases by a BSR having avery large granularity, for example, exceeding the maximum value.

Even in a case where, simply, the maximum value of the buffer valuecorrelated with a BSR index is largely set in order to handle thiscircumstance, the granularity between the buffer values correlated withthe BSR indices becomes rough, and thus it may be difficult to realizethe best uplink scheduling.

In a case where the number of bits of the BSR index is simply set toincrease in order to reduce the granularity between the buffer valuescorrelated with the BSR indices, a new circumstance in whichtransmission efficiency of the buffer status report decreases may occur.Thus, from a viewpoint of transmission efficiency of the buffer statusreport, there is a limit on an increase of the number of bits of the BSRindex to some extents in the fifth-generation mobile communicationsystem.

From the above circumstances, there is a limit on an increase of themaximum value of the buffer value correlated with the BSR index to someextents. Therefore, it is supposed that the buffer value of the wirelessterminal in the fifth-generation mobile communication system exceeds themaximum value in many cases. In a case where the buffer value exceedsthe maximum value, the accuracy of the buffer estimation value of theterminal in the wireless base station decreases by using the BSR indicesindicating buffer values having a very large step size.

In this manner, with the BSR status report having a rough granularity,estimation accuracy regarding the buffer estimation value of thewireless terminal by the wireless base station decreases, and thuscausing the difficulty in the best uplink scheduling. Therefore, it isconcerned that performance of a super high speed and large capacitytransmission service of an uplink in the fifth-generation mobilecommunication system may be degraded by applying the BSR transmissionmethod in the related art.

According to the aspect of the disclosure, a novel BSR transmissiontechnology is provided in which buffer estimation in the wireless basestation may follow variation in a buffer status in the wireless terminaleven in a case where the volume of uplink data which is stored in thetransmission buffer of the wireless terminal and is not transmitted yetmay rapidly increase or decrease. The following is desirably noted. Theabove circumstances may be found in a case where the fifth-generationmobile communication system has been examined from one aspect. Othercircumstances may be found in a case where the communication system hasbeen examined from other aspects. In other words, the features andadvantages of the present invention are not limited to applications forsolving the above-mentioned circumstances, but may be grasped throughembodiments which will be described below.

The configuration of the embodiment which will be described belowrepresents one example for embodying the technical idea of the presentinvention. It is not intended to limit the present invention to theconfiguration of this embodiment. The configuration of the embodimentmay be equally applied to other embodiments falling within the scope ofthe claims. For example, regarding various terms such as a BSR, it isalso considered that the terms may be changed when the specifications ofthe fifth-generation mobile communication system are set after now. Itis also considered that the terms may be changed in a mobilecommunication system subsequent to the fifth-generation mobilecommunication system. In the following disclosure, an example ofprocessing in a medium access control (MAC) layer is used as an exampleof a status report of the transmission buffer of the wireless terminal,but it is desirably noted that there is no intention to limit thedisclosure to the example.

In a wireless communication system 1 according to Example 1, in atransmission sequence of a buffer status report (BSR), in which awireless base station is notified of the size (also referred to as abuffer value) of uplink data which has been stored in a buffer of awireless terminal and is not transmitted yet, a new second field isadded to the BSR in accordance with the buffer value of the wirelessterminal, in addition to a first field for storing a BSR index value.Thus, it is possible to notify the wireless base station of the buffervalue of the wireless terminal with high accuracy, by using the firstfield and the second field of the buffer status report.

FIG. 1 is a diagram illustrating an example of a sequence of BSRtransmission in the wireless communication system 1 according toExample 1. As illustrated in FIG. 1, the wireless communication system 1includes a wireless terminal 10 and a wireless base station 20.

In a case where uplink data which is to be transmitted to the wirelessbase station 20 is generated, the wireless terminal 10 may transmit asignal (SR signal: scheduling request) for requesting allocation ofwireless resources for an uplink from the wireless base station 20 (S1).

The wireless base station 20 may receive the request (SR signal) fromthe wireless terminal 10. The wireless base station checks whether ornot a wireless resource capable of being allocated is provided, forexample. If there is no terminal to which wireless resources are to bepreferentially allocated, the wireless base station may allocatewireless resource to the terminal 10 as a transmission source of the SRsignal. The wireless base station 20 transmits an uplink grant (alsoreferred to as an UL grant or an UL scheduling grant) indicatingwireless resources which have been allocated to the wireless terminal10, to the wireless terminal 10 (S2). The wireless base station 20 doesnot have to transmit the uplink grant.

The wireless terminal 10 may receive the uplink grant from the wirelessbase station 20. Then, the wireless terminal may transmit the latestbuffer status report (BSR) to the wireless base station 20 by using thewireless resources indicated by the uplink grant (S3). The BSR istransmitted at various timings. As described above, the wirelessterminal may perform the BSR transmission sequence based on atransmission period designated by setting information from the basestation 20. The wireless terminal may perform the BSR transmissionsequence in a case where a predetermined event is detected within apredetermined time from a certain time point as a starting point.

The buffer status report (BSR) according to Example 1 includes a firstfield for storing a BSR index corresponding to the size (buffer value)of uplink data which has been stored in a transmission buffer and is nottransmitted yet. The buffer status report (BSR) may include a secondfield for storing an additional index value in a case where the BSRindex stored in the first field has a predetermined first index value.The additional BSR index may be set to indicate a buffer value alongwith the BSR index stored in the first field. In other words, in a casewhere the BSR index stored in the first field has a predetermined firstindex value, the wireless base station is notified of the buffer valueof the wireless terminal by the BSR index (may also be referred to as afirst BSR index) and the additional BSR index (may also be referred toas a second BSR index).

In S3, the wireless terminal 10 may acquire the volume (buffer value) ofuplink data which has been stored in the transmission buffer and is nottransmitted yet, and convert the buffer value into a BSR index inaccordance with a BSR index table.

FIG. 2 is a diagram illustrating an example of the BSR index tableaccording to Example 1. In the BSR index table illustrated in FIG. 2, arange from 0 bytes to 3000000 bytes (=3 Mbytes=3000 Kbytes) is dividedinto ranges of 63 steps, and 63 BSR indices (that is, 0 to 62) arerespectively associated with the ranges. For example, a range of“2439678<BS<=3000000” is associated with a BSR index having an indexvalue of “62”. A buffer value BS belonging to the range of“2439678<BS<=3000000” is any value in a range of being greater than2439678 bytes and equal to or smaller than 3000000 bytes. The last BSRindex (that is, 63) means a buffer value BS exceeding the maximum value(may also be referred to as a maximum buffer value) of a buffer, whichis defined in the BSR index table. In the example in FIG. 2, the maximumbuffer value defined in the BSR index table is “3000000 bytes”. Thevalues in the BSR index table illustrated in FIG. 2 are just examples,and Example 1 is not limited to the values.

It is assumed that the wireless terminal 10 and the wireless basestation 20 in the wireless communication system 1 according to Example 1have the BSR index table as illustrated in FIG. 2.

FIG. 3 is a diagram illustrating an example of the buffer status report(BSR) according to Example 1. The buffer status report (BSR) illustratedin FIG. 3 stores a BSR index indicating a buffer value, for each of oneor more logical channel groups (LCGs). In the example in FIG. 3, thebuffer status report (BSR) includes one or more first fields for storinga BSR index corresponding to any of one or more LCGs.

In the example in FIG. 3, the buffer status report (BSR) may include aplurality of fields including the first field for storing a BSR index,for three LCGs of LCG [0], LCG [1], and LCG [2]. That is, the bufferstatus report (BSR) in FIG. 3 includes four fields from BufferSize [1]to BufferSize [4], as fields for storing information indicating buffervalues for the LCGs. In other words, in the buffer status report (BSR)in FIG. 3, for three LCGs (LCG [0], LCG [1], and LCG [2]), four fieldsin total (BufferSizes [1] to [4]) of three first fields and one secondfield are stored. The number of fields (first field and second field)provided in the buffer status report (BSR) according to the example isnot limited thereto, and may vary.

For example, first fields may be assigned to one or more LCGs in whichthe presence of the first field is indicated by a header portion T101,in ascending order of the LCG numbers. For example, BufferSize [1] maybe used for the first LCG [0], as the first field for storing a BSRindex corresponding to the buffer value for LCG [0]. In the example inFIG. 3, BufferSize [1] as the first field of LCG [0] stores the value of“111110”. The value of “111110” is a value expressed by a binary number,and means “62” when the value of “111110” is converted into a decimalnumber. According to the BSR index table illustrated in FIG. 2, the BSRindex of “62” means that the buffer value exceeds 2439678 bytes and isequal to or smaller than 3000000 bytes.

BufferSize [2] may be used as the first field for storing a BSR indexcorresponding to the buffer value for the second LCG [1]. In the examplein FIG. 3, BufferSize [2] as the first field of LCG [1] stores the valueof “111111”. The value of “111111” is a value expressed by a binarynumber, and means “63” when the value of “111111” is converted into adecimal number. According to the BSR index table illustrated in FIG. 2,the BSR index of “63” means that the buffer value exceeds the maximumvalue (3000000 bytes) of the buffer, which is defined in the BSR indextable.

Therefore, in a case where the BSR index corresponds to a value (forexample, “63”) (may also be referred to as a first index value)indicating a buffer value which exceeds the maximum buffer value, thesecond field for storing an additional index value (may also be referredto as a second BSR index) may be assigned. In the example in FIG. 3,since the BSR index stored in the first field (BufferSize [2]) of LCG[1] corresponds to the first index value, BufferSize [3] is assigned toLCG [1], as the second field for storing an additional index.

BufferSize [3] as the second field of LCG [1] stores the value of“111110”. The value of “111110” is a value expressed by a binary number,and means “62” when the value of “111110” is converted into a decimalnumber. According to the BSR index table illustrated in FIG. 2, the BSRindex of “62” means that the buffer value exceeds 2439678 bytes and isequal to or smaller than 3000000 bytes.

In the example of the buffer status report (BSR) depicted in FIG. 3,BufferSize [2] as the first field and BufferSize [3] as the second fieldare assigned to LCG [1]. With the first field and the second field, itis possible to send a buffer value exceeding the maximum value (may alsobe referred to as the maximum buffer value) of the buffer, which isdefined in the BSR index table, to the wireless base station 20. In theexample in FIG. 3, the BSR index (may also be referred to as the firstBSR index) stored in the first field indicates that the buffer value BSof the wireless terminal 10 exceeds 3000000 bytes. The additional BSRindex (may also be referred to as the second BSR index) stored in thesecond field indicates that a buffer value BS2 corresponding to theamount of the buffer value exceeding 3000000 bytes is in the range of2439678 bytes<BS2<=3000000 bytes. That is, it is understood that thebuffer value BS for LCG [1] is indicated by a value obtained by addingthe maximum value (3000000 byte) to the buffer value BS2 correspondingto the amount of the buffer value exceeding, and is in a range of5439678 bytes<BS<=6000000 bytes.

BufferSize [4] may be used as the first field for the last third LCG[2]. In the example in FIG. 3, the value of “111110” is stored inBufferSize [4] as the first field for LCG [2]. The value of “111110” isa value expressed by a binary number, and is “62” if the value of“111110” is converted into a decimal number. According to the BSR indextable illustrated in FIG. 2, the BSR index of “62” means that the buffervalue BS of the wireless terminal 10 exceeds 2439678 bytes and is equalto or smaller than 3000000 bytes.

The wireless base station 20 which has received the buffer status report(BSR) from the wireless terminal 10 may recognize a LCG for which a BSRindex is stored, by referring to the header portion T101 of a BSR. Inother words, the wireless base station 20 may recognize the number offirst fields provided in a body portion T102 of the BSR, based on theheader portion T101 of the BSR.

The wireless base station 20 may acquire an estimated value (may also bereferred to as a buffer estimation value) of a buffer value for each LCGin the wireless terminal 10 in a manner that the wireless base stationacquires a BSR index from the first field correlated with each LCG andconverts the BSR index into a buffer value in accordance with the BSRindex table illustrated in FIG. 2.

In a case where the BSR index acquired from the first field correspondsto the first index value (for example, maximum value (3000000 bytes) ofthe BSR index table), the wireless base station 20 acquires the secondfield for the LCG correlated with the first field, from the bufferstatus report (BSR) received from the wireless terminal 20. The wirelessbase station 20 converts a second BSR index (may also be referred to asan additional BSR index or an extended BSR index) stored in the secondfield, into a buffer value in accordance with the BSR index table, andthus may recognize an excess buffer amount of the LCG.

The wireless base station 20 may recognize the amount of wirelessresources that a wireless terminal 10 (or an LCG of the wirelessterminal 10) needs to be allocated, by updating the buffer estimationvalue of the wireless terminal 10 based on the latest BSR from thewireless terminal 10. Thus, it is expected that suitable scheduling isperformed. The wireless base station 20 may perform scheduling ofwireless resources based on the latest buffer estimation value and thelike. As a result, in a case where the wireless base station allocateswireless resources to the wireless terminal 10, the wireless basestation transmits an uplink grant (ULgrant) signal (S4).

In S4, the wireless base station 20 may transmit an uplink grant signalindicating the amount of wireless resources allocated for each LCG inthe wireless terminal 10. The uplink grant signal may includeinformation indicating the amount of wireless resources allocated foreach of one or more LCGs.

The wireless terminal 10 may receive the uplink grant from the wirelessbase station 20. The wireless terminal obtains data (may also bereferred to as UL (Uplink) data) the size of which corresponding to theallocated data volume (also referred to as the allocated amount), fromthe transmission buffer. Then, the wireless terminal may transmit datato the base station 20 using the allocated wireless resource (S5).

In the BSR transmission sequence according to Example 1, even in a casewhere the buffer value notified by a BSR exceeds the maximum value (forexample, 3000000 bytes) in the BSR index table, the wireless basestation 20 may estimate the accurate buffer value by a notification ofthe buffer value using both the first field and the second field.

Next, an example of a flow of processing of the wireless terminal 10 inthe BSR transmission sequence according to Example 1 will be described.

FIG. 4 is a diagram illustrating an example of a flow of processing of awireless terminal 10 in a BSR transmission sequence according toExample 1. The flow of the processing illustrated in FIG. 4 may beperformed, for example, when the wireless terminal 10 acquires a BSRindex in an LCG unit. In other words, in a case where it is assumed thatthe wireless terminal acquires BSR indices for a plurality of LCGs, thewireless terminal 10 may perform the processing illustrated in FIG. 4,for each LCG. For easy descriptions, descriptions will be made on theassumption that the wireless terminal 10 performs the processingillustrated in FIG. 4. The wireless terminal 10 may include one or moreprocessor circuits as the subject that performs the processing.

Firstly, the wireless terminal 10 may convert the current buffer valueBS into a BSR index (S101). In S101, the wireless terminal 10 mayacquire the size (may also be referred to as a buffer value, a buffersize value, or a BS value) of uplink data which is stored in thetransmission buffer of a logical channel (LC) belonging to an LCG as aprocessing target and is not transmitted yet. Then, the wirelessterminal may convert the BS value into a BSR index in accordance with aBSR index table. In S101, in a case where a plurality of logicalchannels belonging to the LCG as the processing target is provided, thewireless terminal 10 may set a value obtained by summing buffer valuesof the logical channels, as the BS value.

The wireless terminal 10 may store the BSR index (may also be referredto as a first BSR index) acquired in S101, in the first fieldcorresponding to the LCG as the processing target (S102).

The wireless terminal 10 may determine whether the BSR index acquired inS101 corresponds to the first index value (S103). The first index valueaccording to Example 1 corresponds to, for example, the last BSR indexin the BSR index table. In the example in FIG. 2, the last BSR indexcorresponds to a BSR index of “63” meaning that the buffer value BSexceeds the maximum value (3000000 bytes) of the buffer, which isdefined in the BSR index table. In a case where the BSR index isexpressed by a binary number of six digits, the first index value of“63” is expressed by a bit string in which all six digits are “1”.

In S103, in a case where the BSR index acquired in S101 is equal to thefirst index, the wireless terminal 10 may determine that the BSR indexcorresponds to the first index value (YES in S103). In S103, in a casewhere the BSR index acquired in S101 is not equal to the first indexvalue, the wireless terminal 10 may determine that the BSR index doesnot correspond to the first index value (NO in S103).

In a case where the wireless terminal determines that the BSR indexcorresponds to the first index value (YES in S103), the wirelessterminal 10 acquires an additional BSR index (may also be referred to asa second BSR index) (S104). In S104, the wireless terminal 10 mayacquire an excess buffer value BS2 corresponding to the amount of thebuffer exceeding the maximum buffer value, by subtracting the maximumbuffer value (for example, 3000000 bytes) defined in the BSR index tablefrom the buffer value BS. For example, in a case where the buffer valueBS is “6000000 bytes”, the excess buffer value BS2 is “3000000 bytes”(=6000000 bytes-3000 bytes).

In S104, the wireless terminal 10 may acquire the additional BSR indexby selecting a BSR index corresponding to the excess buffer value BS2with reference to the BSR index table. For example, in a case where theexcess buffer value BS2 is “3000000 bytes”, according to the BSR indextable illustrated in FIG. 2, the additional BSR corresponding to theexcess buffer value BS2 is “62”.

In a case where the wireless terminal has performed the process of S104,the wireless terminal 10 stores the additional BSR index in a secondfield corresponding to the LCG as the processing target (S105).

In a case where it is determined, in S103, that the BSR index (may alsobe referred to as the first BSR index) does not correspond to the firstindex value (NO in S103), the wireless terminal 10 may skip theprocesses of S104 and S105 without assigning the second field for theLCG as the processing target.

The above descriptions are an example of the flow of the processing ofthe wireless terminal 10 in the BSR transmission sequence according toExample 1. Next, a flow of processing of the wireless base station 20will be described.

FIG. 5 is a diagram illustrating a flow of the processing of thewireless base station 20 in the BSR transmission sequence according toExample 1. The flow of the processing illustrated in FIG. 5 may beperformed, for example, when the wireless base station 20 refers to thefirst field of an LCG unit from a BSR received from the wirelessterminal 10. In other words, in a case where the BSR received from thewireless terminal 10 includes one or more fields for each of a pluralityof LCGs, the wireless terminal 10 may perform the processing illustratedin FIG. 5 for each LCG. For easy descriptions, descriptions will be madeon the assumption that the wireless base station 20 performs theprocessing illustrated in FIG. 5. The wireless base station 20 mayinclude one or more processor circuits as the subject that performs theprocessing.

Firstly, the wireless base station 20 acquires a BSR index from thefirst field of a BSR received from the wireless terminal 10 (S201). InS201, in a case where the BSR received from the wireless terminal 10includes a plurality of first fields, the wireless base station 20 mayacquire the BSR index from the first field correlated with the LCG asthe processing target among the first fields in the BSR.

The wireless base station 20 converts the BSR index (may also bereferred to as a first BSR index) acquired in S201 into a buffer valueBS1 in accordance with the BSR index table (S202). For example, in acase where the BSR index is “62”, according to the BSR index tableillustrated in FIG. 2, the buffer value BS1 corresponding to the BSRindex is in a range of “2439678 bytes<BS1<=3000000 bytes”.

The wireless base station 20 determines whether the BSR index acquiredin the process of S201 corresponds to the first index value (S203).Here, the first index value is similar to the first index value in thewireless terminal 10. That is, the first index value according toExample 1 corresponds to the last BSR index in the BSR index table, forexample. In the example in FIG. 2, the last BSR index corresponds to theBSR index of “63” meaning that the buffer value BS1 exceeds the maximumvalue (3000000 bytes) of the buffer, which is defined in the BSR indextable. In a case where the BSR index is expressed by a binary number ofsix digits, the first index value of “63” is expressed by a bit stringin which all six digits are “1”.

In S203, in a case where the BSR index acquired in S201 is equal to thefirst index value, the wireless base station 20 may determine that theBSR index corresponds to the first index value (YES in S203). In S203,in a case where the BSR index acquired in S201 is not equal to the firstindex value, the wireless base station 20 may determine that the BSRindex does not correspond to the first index value (NO in S203).

In a case where the wireless base station determines that the BSR indexcorresponds to the first index value (YES in S203), the wireless basestation 20 acquires an additional BSR index (may also be referred to asa second BSR index) from the second field of the BSR received from thewireless terminal 10 (S204). In S204, in a case where the BSR receivedfrom the wireless terminal 10 includes a plurality of second fields, thewireless base station acquires the additional BSR index from the secondfield correlated with the LCG as the processing target.

The wireless base station 20 converts the additional BSR index acquiredin S204 into a second buffer value BS2 in accordance with the BSR indextable (S205). For example, in a case where the additional BSR index is“62”, according to the BSR index table illustrated in FIG. 2, the secondbuffer value BS2 corresponding to the additional BSR index is in a rangeof “2439678 bytes<BS2<=3000000”.

The wireless base station 20 acquires a buffer estimation value BS ofthe wireless terminal 10 based on the second buffer value BS2 acquiredin S205 and the buffer value BS1 acquired in S202 (S206). Here, thebuffer value BS1 acquired in S202 corresponds to the maximum value ofthe buffer, which is defined in the BSR index table because the BSRindex corresponds to the first index value. That is, according to theBSR index table illustrated in FIG. 2, because the maximum value of thebuffer is “3000000 bytes”, the buffer value BS1 in S206 is “3000000bytes”.

In S206, the wireless base station 20 may acquire the buffer estimationvalue of the wireless terminal 10, for example, by adding the buffervalue BS1 (for example, “3000000 bytes”) acquired in S202 to the secondbuffer value BS2 acquired in S205. For example, in a case where thesecond buffer value BS2 is in a range of “2439678 bytes<BS2<=3000000”,the wireless base station 20 may acquire a range of “5439678bytes<BS<=6000000” as the buffer estimation value BS, by adding thebuffer value BS1 of “3000000 bytes” to each of the upper limit value andthe lower limit value defining the range of the second buffer value BS2.

In a case where it is determined, in S203, that the BSR index does notcorrespond to the first index value (NO in S203), the wireless basestation 20 may skip the processes of S204 to S206 and set the buffervalue BS1 acquired in S202 to be the buffer estimation value BS of thewireless terminal 10.

The above descriptions are an example of the flow of the processing ofthe wireless base station 20 in the BSR transmission sequence accordingto Example 1.

According to an aspect of Example 1 disclosed above, the new secondfield is added to the buffer status report (BSR) for a notification ofthe size (also referred to as the buffer value) of uplink data which hasbeen stored in the buffer of the wireless terminal 10 and is nottransmitted yet, in accordance with the buffer value of the wirelessterminal 10 in addition to the first field for storing the BSR indexvalue. Thus, the wireless terminal 10 may notify the wireless basestation 20 of the buffer value of the wireless terminal 10 with highaccuracy, by using the first field and the second field of the bufferstatus report (BSR). Such an action is useful for maintaining andimproving performance of the super high speed and large capacitytransmission service of an uplink in the fifth-generation mobilecommunication system.

According to another aspect of Example 1 disclosed above, in a casewhere the BSR index stored in the first field of the buffer statusreport (BSR) corresponds to the first index value, the second field forstoring the additional BSR index indicating the extent to which thedegree of the buffer value of the wireless terminal 10 exceeds themaximum buffer value in the BSR index table, is added to the BSR. Thus,the wireless base station 20 may estimate the buffer value of thewireless terminal 10 with high accuracy, by using the values stored inthe first field and the second field of the BSR. Such an action isuseful for maintaining and improving performance of the super high speedand large capacity transmission service of an uplink in thefifth-generation mobile communication system.

According to still another aspect of Example 1 disclosed above, theadditional BSR stored in the second field of the buffer status report(BSR) corresponds to a buffer value (may also be referred to as theexcess buffer value) exceeding the maximum buffer value in the BSR indextable, in the buffer value of the wireless terminal 10. Thus, thewireless base station 20 may estimate the buffer value of the wirelessterminal 10 with high accuracy, by using the values stored in the firstfield and the second field of the BSR. Such an action is useful formaintaining and improving performance of the super high speed and largecapacity transmission service of an uplink in the fifth-generationmobile communication system.

Example 2

In a wireless communication system 1 according to Example 2, in a casewhere the BSR index stored in the first field included in buffer statusinformation corresponds to the first index value, an additional BSRindex (may also be referred to as an additional index value) associatedwith a predetermined coefficient (may also be referred to as a BSRcoefficient) is stored in the second field which has been newly added.In this case, the buffer value of the wireless terminal 10 is indicatedby a result obtained by multiplying the buffer value corresponding tothe BSR index of the first field and the BSR coefficient correspondingto the additional BSR index of the second field. Thus, since the buffervalue of the wireless terminal 10 is indicated using the first field andthe second field of the BSR, the wireless base station 20 may estimatethe buffer value of the wireless terminal 10 with high accuracy.

FIG. 6 is a diagram illustrating an example of a BSR index tableaccording to Example 2. In the BSR index table according to Example 2, apredetermined coefficient (may also be referred to as a BSR coefficient)is associated with some of one or more BSR indices defined in the BSRindex table. In the BSR index table illustrated in FIG. 6, “×1.5”(meaning a magnification of 1.5), “×2.0” (meaning a magnification of2.0), “×2.5” (meaning a magnification of 2.5), and “×3.0” (meaning amagnification of 3.0), as the BSR coefficients, are associated with thefour BSR indices of “252” to “255” among 256 BSR indices of “0” to“255”, respectively.

In the BSR index table illustrated in FIG. 6, buffer values areassociated with 252 BSR indices of “0” to “251”, respectively. That is,subranges obtained by dividing a range of “0 bytes” to “96000000 bytes”into 251 ranges are correlated with the 251 BSR indices of “0” to “250”,respectively. A status where a buffer value exceeds “96000000 bytes”being the maximum value of the buffer, which is defined in the BSR indextable is correlated with the last BSR index of “251” among the 252 BSRindices of “0” to “251”.

In the example in FIG. 6, the number of BSR indices is extended to 256in comparison to the example of the BSR index table according to Example1, which is illustrated in FIG. 2. In other words, the bit length of theBSR index is extended to 8 bits (bit string of 8 digits). In the examplein FIG. 6, the maximum value of the buffer, which is defined in the BSRindex table is extended to 96000000 bytes. However, it is desirablynoted that Example 2 is not limited to such specific values.

It is assumed that a wireless terminal 10 and a wireless base station 20in the wireless communication system 1 according to Example 2 have a BSRindex table as illustrated in FIG. 6.

FIG. 7 is a diagram illustrating an example of a buffer status reportaccording to Example 2. Similar to the example in FIG. 3, the bufferstatus report (BSR) illustrated in FIG. 7 stores a BSR index indicatinga buffer value, for each of one or more logical channel groups (LCGs).Also in the example in FIG. 7, the buffer status report (BSR) has aheader portion T101A and a body portion T102A. The header portion mayindicate whether or not the first field for storing a BSR index isprovided for each of one or more LCGs. The body portion T102A mayinclude the first field corresponding to any of one or more LCGs.

In the header portion T101A illustrated in FIG. 7, for 8 LCGs from LCG[0] to LCG [7], a value is set, where the value indicates that the firstfield is provided in the body portion T102A (that is, “1”) or the valueindicates that the first field is not provided in the body portion T102A(that is, “0”). In the example in FIG. 7, it is represented that thefirst field is provided in the body portion T102A for LCG [4], LCG [1],and LCG [0].

The body portion T102A illustrated in FIG. 7 includes four fields fromBufferSize [1] to BufferSize [4], as fields for storing informationindicating buffer values for the LCGs, regarding LCG [4], LCG [1], andLCG [0] in which the presence of the first field is indicated by theheader portion T101A. That is, in the example in FIG. 7, three firstfields and one second field are stored in the body portion T102A of aBSR, for the three LCGs (LCG [4], LCG [1], and LCG [0]). The number offields (first field and second field) provided in the buffer statusreport (BSR) according to the example is not limited thereto, and mayvary.

For example, first fields may be assigned to one or more LCGs in whichthe presence of the first field is indicated by the header portionT101A, in ascending order of the LCG numbers. BufferSize [1] may be usedfor the first LCG [0], as the first field for storing a BSR indexcorresponding to the buffer value for LCG [0]. In the example in FIG. 7,the value of “11111010” is stored in BufferSize [1] as the first fieldfor LCG [0]. The value of “11111010” is a value expressed by a binarynumber, and is “250” if the value of “11111010” is converted into adecimal number. According to the BSR index table illustrated in FIG. 6,the BSR index of “250” means that the buffer value BS of the wirelessterminal 10 exceeds 90089323 bytes and is equal to or smaller than96000000 bytes.

BufferSize [2] may be used as the first field for storing a BSR indexcorresponding to the buffer value for the second LCG [1]. In the examplein FIG. 7, the value of “11111011” is stored in BufferSize [2] as thefirst field for LCG [1]. The value of “11111011” is a value expressed bya binary number, and is “251” if the value of “111110111” is convertedinto a decimal number. According to the BSR index table illustrated inFIG. 6, the BSR index of “251” means that the buffer value exceeds themaximum value (96000000 bytes) of the buffer, which is defined in theBSR index table.

Therefore, in a case where the BSR index corresponds to a value (forexample, “251” and “11111011” if being expressed by a binary number)(may also be referred to as a first index value) indicating that thebuffer value exceeds the maximum value of the buffer value, a secondfield for storing an additional index (may also be referred to as asecond BSR index) is assigned. In the example in FIG. 7, since the BSRindex stored in the first field (BufferSize [2]) for LCG [1] correspondsto the first index value, BufferSize [3] is assigned to LCG [1], as thesecond field for storing an additional index.

The value of “11111101” is stored in BufferSize [3] as the second fieldof LCG [1]. The value of “11111101” is a value expressed by a binarynumber, and is “253” if the value of “11111101” is converted into adecimal number. According to the BSR index table illustrated in FIG. 6,the BSR index of “253” is correlated with the BSR coefficient of “×2.0”(meaning a magnification of 2.0).

According to the example of the buffer status report (BSR) in FIG. 7,BufferSize [2] as the first field and BufferSize [3] as the second fieldare assigned to LCG [1]. With the first field and the second field, itis possible to send a buffer value exceeding the maximum value (96000000bytes) of the buffer, which is defined in the BSR index table, to thewireless base station 20. In the example in FIG. 7, the BSR index (mayalso be referred to as the first BSR index) stored in the first fieldindicates that the buffer value BS of the wireless terminal 10 exceeds96000000 bytes. The additional BSR index (may also be referred to as thesecond BSR index) stored in the second field may indicate the degree ofthe buffer value of the wireless terminal 10 exceeding 96000000 bytes.For example, it is represented that the buffer value BS for LCG [1] isin a range of 96000000 bytes<BS<=192000000 bytes, based on a resultobtained by multiplying the buffer value (96000000 bytes) correspondingto the BSR index in the first field, by the BSR coefficient (2.0)corresponding to the additional BSR index in the second field.

Alternatively, the lower limit value of the buffer value BS of thewireless terminal 10 may be indicated based on the BSR coefficientcorrelated with a BSR index which is smaller than the additional BSRindex stored in the second field by one, among the BSR indicescorrelated in the BSR coefficients in the BSR index table. For example,in the example in FIG. 7, the additional BSR index stored in the secondfield is “253” (“11111101” when being expressed by a binary number).According to the BSR index table illustrated in FIG. 6, a BSR indexwhich is smaller than the additional BSR index of “253” by one is “252”,and a BSR coefficient corresponding to the BSR index of “252” is “×1.5”.According to this example, it is understood that the lower limit valueof the buffer value BS of the wireless terminal 10 is “144000000 bytes”,based on a result obtained by multiplying a buffer value of “96000000bytes” corresponding to the BSR index of “251” in the first field by theBSR coefficient of “×1.5”. Thus, it is understood that the buffer valueBS of the wireless terminal 10 is in a range of 144000000bytes<BS<=192000000 bytes.

BufferSize [4] may be used as the first field for the last third LCG[4]. In the example in FIG. 7, the value [11111010] is stored inBufferSize [4] as the first field for LCG [4]. The value of “11111010”is a value expressed by a binary number, and is “250” if the value of“11111010” is converted into a decimal number. According to the BSRindex table illustrated in FIG. 6, the BSR index of “250” means that thebuffer value BS of the wireless terminal 10 exceeds 90089323 bytes andis equal to or smaller than 96000000 bytes.

Next, an example of a flow of processing of the wireless terminal 10 ina BSR transmission sequence according to Example 2 will be described.

FIG. 8 is a diagram illustrating an example of the flow of theprocessing of the wireless terminal 10 in the BSR transmission sequenceaccording to Example 2. The flow of the processing illustrated in FIG. 8may be performed, for example, when the wireless terminal 10 acquires aBSR index in an LCG unit. In other words, in a case where it is assumedthat the wireless terminal acquires BSR indices for a plurality of LCGs,the wireless terminal 10 may perform the processing illustrated in FIG.8, for each LCG. For easy descriptions, descriptions will be made on theassumption that the wireless terminal 10 performs the processingillustrated in FIG. 8. The wireless terminal 10 may include one or moreprocessor circuits as the subject that performs the processing.

Firstly, the wireless terminal 10 converts the current buffer value BSinto a BSR index (S101). In S101, the wireless terminal 10 may acquirethe size (may also be referred to as a buffer value, a buffer sizevalue, or a BS value) of uplink data which is stored in the transmissionbuffer of a logical channel (LC) belonging to an LCG as a processingtarget and is not transmitted yet. Then, the wireless terminal mayconvert the BS value into a BSR index in accordance with a BSR indextable. In S101, in a case where a plurality of logical channelsbelonging to the LCG as the processing target is provided, the wirelessterminal 10 may set a value obtained by summing buffer values of thelogical channels, as the BS value.

The wireless terminal 10 stores the BSR index (may also be referred toas a first BSR index) acquired in S101, in the first field correspondingto the LCG as the processing target (S102).

The wireless terminal 10 determines whether the BSR index acquired inS101 corresponds to the first index value (S103). The first index valuecorresponds to, for example, the last BSR index among one or more BSRindices correlated with the buffer values in the BSR index table. In theexample in FIG. 6, the last BSR index corresponds to a BSR index of“251” meaning that the buffer value BS exceeds the maximum value(96000000 bytes) of the buffer, which is defined in the BSR index table.In other words, in the example in FIG. 6, the first index value may be“251”.

In S103, in a case where the BSR index acquired in S101 is equal to thefirst index, the wireless terminal 10 may determine that the BSR indexcorresponds to the first index value (YES in S103). In S103, in a casewhere the BSR index acquired in S101 is not equal to the first indexvalue, the wireless terminal 10 may determine that the BSR index doesnot correspond to the first index value (NO in S103).

In a case where the wireless terminal determines that the BSR indexcorresponds to the first index value (YES in S103), the wirelessterminal 10 acquires an additional BSR index (may also be referred to asa second BSR index) (S104A). In S104A, the wireless terminal 10 maymultiply the buffer value of “96000000 bytes” (may also be referred toas the maximum buffer value) corresponding to the BSR index of “251” inthe first field, by BSR coefficients which are respectively correlatedwith four BSR indices of the BSR index of “251” to the BSR index of“255”, in ascending order. In S104A, the wireless terminal 10 selects aBSR index corresponding to the BSR coefficient which causes amultiplication result of the maximum buffer value and the BSRcoefficient to be equal to or greater than the buffer value BS of thewireless terminal 10 for the first time, as the additional BSR index.For example, in a case where the buffer value BS of the wirelessterminal 10 is “192000000 bytes”, Multiplication result [1] of the firstBSR coefficient of “×1.5” in ascending order and the maximum buffervalue of “96000000 bytes” is “144000000 bytes”, and this does notsatisfy a condition of the buffer value BS<=Multiplication result [1].Next, Multiplication result [2] of the second BSR coefficient of “×2.0”in ascending order and the maximum buffer value of “96000000 bytes” is“192000000 bytes”, and this satisfies the condition of the buffer valueBS<=Multiplication result [2]. Therefore, the wireless terminal 10 mayselect the BSR index of “253” corresponding to the second BSRcoefficient of “×2.0”, as the additional BSR index. In this case,multiplication using a BSR coefficient subsequent to the third BSRcoefficient may be omitted.

In a case where the wireless terminal has performed the process ofS104A, the wireless terminal 10 stores the additional BSR index in thesecond field corresponding to the LCG as the processing target (S105).

In a case where it is determined, in S103, that the BSR index (may alsobe referred to as the first BSR index) does not correspond to the firstindex value (NO in S103), the wireless terminal 10 may skip theprocesses of S104 and S105 without assigning the second field for theLCG as the processing target.

The above descriptions are an example of the flow of the processing ofthe wireless terminal 10 in the BSR transmission sequence according toExample 2. Next, a flow of processing of the wireless base station 20will be described.

FIG. 9 is a diagram illustrating a flow of the processing of thewireless base station 20 in the BSR transmission sequence according toExample 2. The flow of the processing illustrated in FIG. 9 may beperformed, for example, when the wireless base station 20 refers to thefirst field in an LCG unit from a BSR received from the wirelessterminal 10. In other words, in a case where the BSR received from thewireless terminal 10 includes one or more fields for each of a pluralityof LCGs, the wireless terminal 10 may perform the processing illustratedin FIG. 9 for each LCG. For easy descriptions, descriptions will be madeon the assumption that the wireless base station 20 performs theprocessing illustrated in FIG. 9. The wireless base station 20 mayinclude one or more processor circuits as the subject that performs theprocessing.

Firstly, the wireless base station 20 acquires a BSR index from thefirst field of a BSR received from the wireless terminal 10 (S201). InS201, in a case where the BSR received from the wireless terminal 10includes a plurality of first fields, the wireless base station 20 mayacquire the BSR index from the first field correlated with the LCG asthe processing target among the first fields in the BSR.

The wireless base station 20 converts the BSR index (may also bereferred to as a first BSR index) acquired in S201 into a buffer valueBS1 (may also be referred to as a first buffer value) in accordance withthe BSR index table (S202). For example, in a case where the BSR indexis “250”, according to the BSR index table illustrated in FIG. 6, thebuffer value BS1 corresponding to the BSR index is in a range of“90089323 bytes<BS1<=96000000 bytes”.

The wireless base station 20 determines whether the BSR index acquiredin the process of S201 corresponds to the first index value (S203).Here, the first index value is similar to the first index value in thewireless terminal 10. That is, the first index value corresponds to, forexample, the last BSR index among one or more BSR indices correlatedwith the buffer values in the BSR index table. In the example in FIG. 6,the last BSR index corresponds to the BSR index of “251” meaning thatthe buffer value BS1 exceeds the maximum value (96000000 bytes) of thebuffer, which is defined in the BSR index table. In other words, in theexample in FIG. 6, the first index value may be “251”.

In S203, in a case where the BSR index acquired in S201 is equal to thefirst index value, the wireless base station 20 may determine that theBSR index corresponds to the first index value (YES in S203). In S203,in a case where the BSR index acquired in S201 is not equal to the firstindex value, the wireless base station 20 may determine that the BSRindex does not correspond to the first index value (NO in S203).

In a case where the wireless base station determines that the BSR indexcorresponds to the first index value (YES in S203), the wireless basestation 20 acquires an additional BSR index (may also be referred to asa second BSR index) from the second field of the BSR received from thewireless terminal 10 (S204). In S204, in a case where the BSR receivedfrom the wireless terminal 10 includes a plurality of second fields, thewireless base station acquires the additional BSR index from the secondfield correlated with the LCG as the processing target.

The wireless base station 20 converts the additional BSR index acquiredin S204 into a BSR coefficient in accordance with the BSR index table(S205A). For example, in a case where the additional BSR index is “253”,according to the BSR index table illustrated in FIG. 6, the BSRcoefficient corresponding to the additional BSR index is “×2.0”.

The wireless base station 20 acquires a buffer estimation value of thewireless terminal 10 based on the BSR coefficient acquired in S205A andthe buffer value BS1 acquired in S202 (S206A). Here, since the BSR indexcorresponds to the first index value, the buffer value BS acquired inS202 corresponds to the maximum value of the buffer, which is defined inthe BSR index table. That is, according to the BSR index tableillustrated in FIG. 6, because the maximum value of the buffer is“96000000 bytes”, the buffer value BS1 in S206A is “96000000 bytes”.

In S206A, the wireless base station 20 may acquire the buffer estimationvalue BS of the wireless terminal 10 by multiplying the buffer value BS1(for example, “96000000 bytes”) acquired in S202 by the BSR coefficientacquired in S205A, for example. For example, the wireless terminal 10may acquire “192000000 bytes” being an upper limit of the bufferestimation value BS, by multiplying the buffer value BS1 of “96000000bytes” acquired in S202 by the BSR coefficient of “×2.0” acquired inS205. In this case, a lower limit of the buffer estimation value BS maybe set to “96000000 bytes” being the buffer value BS1 acquired in S202.That is, the wireless base station 20 may acquire a range of “96000000bytes<BS<=192000000 bytes” as the buffer estimation value BS, based onthe BSR coefficient and the buffer value BS1.

In S206A, the wireless base station 20 may acquire the lower limit ofthe buffer estimation value BS of the wireless terminal 10 based on theBSR coefficient correlated with a BSR index which is smaller than theadditional BSR index acquired from the second field of the BSR in S204,by one, among the BSR indices correlated in the BSR coefficients in theBSR index table. For example, in the example in FIG. 7, the additionalBSR index acquired from the second field of the BSR is “253” (“11111101”when being expressed by a binary number). According to the BSR indextable illustrated in FIG. 6, a BSR index which is smaller than theadditional BSR index of “253” by one is “252”, and a BSR coefficientcorresponding to the BSR index of “252” is “×1.5”. In this example, thewireless base station 20 acquires “144000000 bytes” as the lower limitvalue of the buffer estimation value BS, based on a result obtained bymultiplying “96000000 bytes” being the buffer value BS1 acquired inS202, by the BSR coefficient of “×1.5”. That is, the wireless basestation 20 may acquire a range of “144000000 bytes<BS<=192000000 bytes”as the buffer estimation value BS, based on the BSR coefficient and thebuffer value BS1.

In a case where it is determined, in S203, that the BSR index does notcorrespond to the first index value (NO in S203), the wireless basestation 20 may skip the processes of S204 to S206A and set the buffervalue BS1 acquired in S202 to be the buffer estimation value BS of thewireless terminal 10.

The above descriptions are an example of the flow of the processing ofthe wireless base station 20 in the BSR transmission sequence accordingto Example 2.

According to an aspect of Example 2 disclosed above, the new secondfield is added to the buffer status report (BSR) for a notification ofthe size (also referred to as the buffer value) of uplink data which hasbeen stored in the buffer of the wireless terminal 10 and is nottransmitted yet, in accordance with the buffer value of the wirelessterminal in addition to the first field for storing the BSR index value.Thus, the wireless terminal 10 may notify the wireless base station 20of the buffer value of the wireless terminal 10 with high accuracy, byusing the first field and the second field of the buffer status report(BSR). Such an action is useful for maintaining and improvingperformance of the super high speed and large capacity transmissionservice of an uplink in the fifth-generation mobile communicationsystem.

According to another aspect of Example 2 disclosed above, in a casewhere the BSR index stored in the first field of the buffer statusreport (BSR) corresponds to the first index value, the second field forstoring the additional BSR index indicating the degree of the buffervalue of the wireless terminal 10 exceeding the maximum buffer value inthe BSR index table, is added to the BSR. Thus, the wireless basestation 20 may estimate the buffer value of the wireless terminal 10with high accuracy, by using the values stored in the first field andthe second field of the BSR. Such an action is useful for maintainingand improving performance of the super high speed and large capacitytransmission service of an uplink in the fifth-generation mobilecommunication system.

According to still another aspect of Example 2 disclosed above, theadditional BSR stored in the second field of the buffer status report(BSR) corresponds to a BSR coefficient indicating the degree of thebuffer value of the wireless terminal 10 exceeding the maximum buffervalue in the BSR index table. Thus, the wireless base station 20 mayestimate the buffer value of the wireless terminal 10 with highaccuracy, by using the values stored in the first field and the secondfield of the BSR. Such an action is useful for maintaining and improvingperformance of the super high speed and large capacity transmissionservice of an uplink in the fifth-generation mobile communicationsystem.

Example 3

In a wireless communication system 1 according to Example 3, the maximumbuffer value may be set for each logical channel group (LCG) of anuplink. Thus, it is possible to transmit a buffer status report using aBSR index table (may also be referred to as a conversion table) fordefining the proper maximum buffer value, in accordance withcharacteristics of a wireless service of each LCG. Therefore, it ispossible to notify a wireless base station 20 of the buffer value of awireless terminal 10 with high accuracy.

FIG. 10 is a diagram illustrating an example of a BSR index tableaccording to Example 3. In the BSR index table illustrated in FIG. 10, arange from 0 bytes to 192000000 bytes (=192 Mbytes=192000 Kbytes) isdivided into ranges of 63 steps, and 63 BSR indices (that is, 0 to 62)are respectively associated with the ranges. For example, a range of“145848796<BS<=192000000” is associated with a BSR index having an indexvalue of “62”. A buffer value BS belonging to the range of“145848796<BS<=192000000” is any value in a range of being greater than145848796 bytes and equal to or smaller than 192000000 bytes. The lastBSR index (that is, 63) means a buffer value BS exceeding the maximumvalue (may also be referred to as a maximum buffer value) of a buffer,which is defined in the BSR index table. In the example in FIG. 10, themaximum buffer value defined in the BSR index table is “192000000bytes”. The values in the BSR index table illustrated in FIG. 10 arejust examples, and Example 3 is not limited to the values.

It is assumed that a wireless terminal 10 and a wireless base station 20in the wireless communication system 1 according to Example 3 have theBSR index table (may also be referred to as a first BSR index table or afirst conversion table) illustrated in FIG. 2 and the BSR index table(may also be referred to as a second BSR index table, a secondconversion table, an extended BSR index table, or an extended conversiontable) illustrated in FIG. 10. The maximum buffer value in the firstconversion table in the example in FIG. 2 is “3000000 bytes”, and themaximum buffer value in the second conversion table in the example inFIG. 10 is “192000000 bytes”. That is, the maximum buffer value in thefirst conversion table is different from the maximum buffer value in thesecond conversion table.

FIG. 11 is a diagram illustrating an example of a flow of processing ofthe wireless terminal 10 in a BSR transmission sequence according toExample 3. The flow of the processing illustrated in FIG. 11 may beperformed, for example, when the wireless terminal 10 acquires a BSRindex in an LCG unit. In other words, in a case where it is assumed thatthe wireless terminal acquires BSR indices for a plurality of LCGs, thewireless terminal 10 may perform the processing illustrated in FIG. 11,for each LCG. For easy descriptions, descriptions will be made on theassumption that the wireless terminal 10 performs the processingillustrated in FIG. 11. The wireless terminal 10 may include one or moreprocessor circuits as the subject that performs the processing.

Firstly, the wireless terminal 10 converts the current buffer value BSinto a BSR index in accordance with the conversion table depending on anLCG as a processing target (S101B). In S101B, the wireless terminal 10may select a conversion table depending on the LCG as the processingtarget, based on settings from a higher layer.

FIG. 12 is a diagram illustrating an example of setting informationregarding a correspondence relation between the conversion tableaccording to Example 3 and LCGs. In the example in FIG. 12 the maximumbuffer value (BS Max value) is set for each logical channel group (LCG).For example, the maximum buffer value of “3000000 bytes” (may also bereferred to as a first value) is set for LCG [0], LCG [2], LCG [3], LCG[4], and LCG [5]. The maximum buffer value of “192000000 bytes” (mayalso be referred to as a second value) which is greater than the firstvalue is set for LCG [1]. The example in FIG. 12 represents the conceptof the setting information, and the above-described values does not haveto be set. For example, the first value and the second value may bedistinguished from each other by setting numerical values of one bit(that is, “1” and “0”), respectively. In other words, whether themaximum buffer value correlated with an LCG is the first value or thesecond value may be set by associating “1” or “0” with each LCG insetting information.

It is assumed that the wireless terminal 10 and the wireless basestation 20 in the wireless communication system 1 according to Example 3have setting information illustrated in FIG. 12. The wireless terminal10 may acquire the setting information illustrated in FIG. 12, by aradio resource control (RRC) message transmitted from the wireless basestation 20. In other words, the wireless base station 20 may transmit anRRC message including the setting information illustrated in FIG. 12 tothe wireless terminal 10. Such an RRC message may include settinginformation in which the maximum buffer value for each of a plurality ofLCGs is defined, or may include setting information in which the maximumbuffer value for one LCG is defined.

In S101B, the wireless terminal 10 may acquire the maximum buffer valuecorresponding to an LCG as the processing target, based on the settinginformation illustrated in FIG. 12. The wireless terminal may select aconversion table depending on the LCG as the processing target byselecting a conversion table in which the maximum buffer value isdefined among a plurality of conversion tables. For example, in a casewhere an LCG as the processing target is LCG [0], the maximum buffervalue corresponding to LCG [0] is “3000000 bytes” according to theexample in FIG. 12. Thus, the wireless terminal 10 selects a firstconversion table. In a case where the LCG as the processing target isLCG [1], the maximum buffer value corresponding to LCG [1] is “192000000bytes” according to the example in FIG. 12. Thus, the wireless terminal10 selects a second conversion table.

In S101B, the wireless terminal 10 may acquire the size (may also bereferred to as a buffer value, a buffer size value, or a BS value) ofuplink data which is stored in the transmission buffer of a logicalchannel (LC) belonging to an LCG as a processing target and is nottransmitted yet. Then, the wireless terminal may convert the BS valueinto a BSR index in accordance with the conversion table (may also bereferred to as the BSR index table) depending on the LCG as theprocessing target. In S101B, in a case where a plurality of logicalchannels belonging to the LCG as the processing target is provided, thewireless terminal 10 may set a value obtained by summing buffer valuesof the logical channels, as the BS value.

The wireless terminal 10 stores the BSR index (may also be referred toas a first BSR index) acquired in S101B, in the first fieldcorresponding to the LCG as the processing target (S102).

The wireless terminal 10 determines whether the BSR index acquired inS101B corresponds to the first index value (S103). The first index valueaccording to Example 3 corresponds to, for example, the last BSR indexamong one or more BSR indices correlated with the buffer values in theconversion table (may also be referred to as the BSR index table)depending on the LCG as the processing target. In the example in FIG. 2,the last BSR index in the first conversion table is “63”. In the examplein FIG. 10, the last BSR index in the second conversion table is “63”.The last BSR index in the example in FIG. 2 and the last BSR index inthe example in FIG. 10 are “63”, that is, equal to each other. However,it is desirably noted that the maximum buffer value (192000000 bytes) inthe second conversion table is greater than the maximum buffer value(3000000 bytes) in the first conversion table.

In S103, in a case where the BSR index acquired in S101B is equal to thefirst index value, the wireless terminal 10 may determine that the BSRindex corresponds to the first index value (YES in S103). In S103, in acase where the BSR index acquired in S101 is not equal to the firstindex value, the wireless terminal 10 may determine that the BSR indexdoes not correspond to the first index value (NO in S103).

In a case where the wireless terminal determines that the BSR indexcorresponds to the first index value (YES in S103), the wirelessterminal 10 acquires an additional BSR index (may also be referred to asa second BSR index) in accordance with the conversion table depending onthe LCG as the processing target (5104B). In 5104B, the wirelessterminal 10 may acquire an excess buffer value BS2 corresponding to theamount of the buffer exceeding the maximum buffer value, by subtractingthe maximum buffer value defined in the conversion table depending onthe LCG as the processing target from the buffer value BS. For example,in a case where the conversion table depending on the LCG as theprocessing target is the first conversion table, according to theexample in FIG. 2, the maximum buffer value is “3000000 bytes”. If thebuffer value BS is “6000000 bytes”, the excess buffer value BS2 is“3000000 bytes” (=6000000 bytes-3000 bytes). According to the example inFIG. 10, if the buffer value BS is “6000000 bytes”, it is desirablynoted that the excess buffer value BS2 is not provided in the secondconversion table.

In S104B, the wireless terminal 10 may acquire an additional BSR indexby selecting a BSR index corresponding to the excess buffer value BS2 inaccordance with the conversion table depending on the LCG as theprocessing target. For example, in a case where the excess buffer valueBS2 is “3000000 bytes”, according to the second conversion tableillustrated in FIG. 2, the additional BSR corresponding to the excessbuffer value BS2 is “62”.

In a case where the wireless terminal has performed the process ofS104B, the wireless terminal 10 stores the additional BSR index in thesecond field corresponding to the LCG as the processing target (S105).

In a case where it is determined, in S103, that the BSR index (may alsobe referred to as the first BSR index) does not correspond to the firstindex value (NO in S103), the wireless terminal 10 may skip theprocesses of S104 and S105 without assigning the second field for theLCG as the processing target.

The above descriptions are an example of the flow of the processing ofthe wireless terminal 10 in the BSR transmission sequence according toExample 3. Next, a flow of processing of the wireless base station 20will be described.

FIG. 13 is a diagram illustrating a flow of processing of the wirelessbase station 20 in the BSR transmission sequence according to Example 3.The flow of the processing illustrated in FIG. 13 may be performed, forexample, when the wireless base station 20 refers to the first field ofan LCG unit from a BSR received from the wireless terminal 10. In otherwords, in a case where the BSR received from the wireless terminal 10includes one or more fields for each of a plurality of LCGs, thewireless terminal 10 may perform the processing illustrated in FIG. 13for each LCG. For easy descriptions, descriptions will be made on theassumption that the wireless base station 20 performs the processingillustrated in FIG. 13. The wireless base station 20 may include one ormore processor circuits as the subject that performs the processing.

Firstly, the wireless base station 20 acquires a BSR index from thefirst field of a BSR received from the wireless terminal 10 (S201). InS201, in a case where the BSR received from the wireless terminal 10includes a plurality of first fields, the wireless base station 20 mayacquire the BSR index from the first field correlated with the LCG asthe processing target among the first fields in the BSR.

The wireless base station 20 converts the BSR index (may also bereferred to as a first BSR index) acquired in S201 into a buffer valueBS1 in accordance with the conversion table depending on the LCG as theprocessing target (S202B). For example, in a case where the BSR index is“62”, according to the first conversion table illustrated in FIG. 2, thebuffer value BS1 corresponding to the BSR index is in a range of“2439678 bytes<BS1<=3000000 bytes”. A method of selecting a conversiontable depending on an LCG as the processing target is similar to theprocess of S101B in the wireless terminal 10. Thus, detaileddescriptions thereof will be omitted.

The wireless base station 20 determines whether the BSR index acquiredin the process of S201 corresponds to the first index value (S203).Here, the first index value is similar to the first index value in thewireless terminal 10. That is, the first index value according toExample 3 corresponds to, for example, the last BSR index in theconversion table depending on the LCG as the processing target. In theexample in FIG. 2, the last BSR index in the first conversion table is“63”. In the example in FIG. 10, the last BSR index in the secondconversion table is “63”. The last BSR index in the example in FIG. 2and the last BSR index in the example in FIG. 10 are “63”, that is,equal to each other. However, it is desirably noted that the maximumbuffer value (192000000 bytes) in the second conversion table is greaterthan the maximum buffer value (3000000 bytes) in the first conversiontable.

In S203, in a case where the BSR index acquired in S201 is equal to thefirst index value, the wireless base station 20 may determine that theBSR index corresponds to the first index value (YES in S203). In S203,in a case where the BSR index acquired in S201 is not equal to the firstindex value, the wireless base station 20 may determine that the BSRindex does not correspond to the first index value (NO in S203).

In a case where the wireless base station determines that the BSR indexcorresponds to the first index value (YES in S203), the wireless basestation 20 acquires an additional BSR index (may also be referred to asa second BSR index) from the second field of the BSR received from thewireless terminal 10 (S204). In S204, in a case where the BSR receivedfrom the wireless terminal 10 includes a plurality of second fields, thewireless base station acquires the additional BSR index from the secondfield correlated with the LCG as the processing target.

The wireless base station 20 converts the additional BSR index acquiredin S204 into a second buffer value BS2 in accordance with the conversiontable depending on the LCG as the processing target (S205B). Forexample, in a case where the additional BSR index is “62”, according tothe first conversion table illustrated in FIG. 2, the second buffervalue BS2 corresponding to the additional BSR index is in a range of“2439678 bytes<BS2<=3000000”.

The wireless base station 20 acquires a buffer estimation value BS ofthe wireless terminal 10 based on the second buffer value BS2 acquiredin S205B and the buffer value BS1 acquired in S202B (S206). Here, sincethe BSR index corresponds to the first index value, the buffer value BS1acquired in S202B corresponds to the maximum buffer value defined in theconversion table depending on the LCG as the processing target. That is,according to the first conversion table illustrated in FIG. 2, becausethe maximum value of the buffer is “3000000 bytes”, the buffer value BS1in S206 is “3000000 bytes”. According to the second conversion tableillustrated in FIG. 10, because the maximum value of the buffer is“192000000 bytes”, the buffer value BS1 in S206 is “192000000 bytes”.

In S206, the wireless base station 20 may acquire the buffer estimationvalue BS of the wireless terminal 10, for example, by adding the buffervalue BS1 (for example, “3000000 bytes”) acquired in S202B to the secondbuffer value BS2 acquired in S205B. For example, in a case where thesecond buffer value BS2 is in a range of “2439678 bytes<BS2<=3000000”,according to the first conversion table illustrated in FIG. 2, thewireless base station 20 may acquire a range of “5439678bytes<BS<=6000000” as the buffer estimation value BS, by adding thebuffer value BS1 of “3000000 bytes” to each of the upper limit value andthe lower limit value defining the range of the second buffer value BS2.

In a case where it is determined, in S203, that the BSR index does notcorrespond to the first index value (NO in S203), the wireless basestation 20 may skip the processes of S204 to S206 and set the buffervalue BS1 acquired in S202B to be the buffer estimation value BS of thewireless terminal 10.

The above descriptions are an example of the flow of the processing ofthe wireless base station 20 in the BSR transmission sequence accordingto Example 3.

According to an aspect of Example 3 disclosed above, the new secondfield is added to the buffer status report (BSR) for a notification ofthe size (also referred to as the buffer value) of uplink data which hasbeen stored in the buffer of the wireless terminal 10 and is nottransmitted yet, in accordance with the buffer value of the wirelessterminal 10 in addition to the first field for storing the BSR indexvalue. Thus, the wireless terminal 10 may notify the wireless basestation 20 of the buffer value of the wireless terminal 10 with highaccuracy, by using the first field and the second field of the bufferstatus report (BSR). Such an action is useful for maintaining andimproving performance of the super high speed and large capacitytransmission service of an uplink in the fifth-generation mobilecommunication system.

According to another aspect of Example 3 disclosed above, it is possibleto set the maximum buffer value in the conversion table (may also bereferred to as the BSR index table) for each logical channel group (LCG)of an uplink. For example, if the second conversion table in which thelarge maximum buffer value is defined among a plurality of conversiontables is set to be assigned to an LCG to which a logical channel usedin a super high speed and large capacity transmission service such aseMBB belongs, it is possible to suppress an occurrence of a situation inwhich the buffer value of the wireless terminal 10 exceeds the maximumbuffer value defined in the conversion table. If the first conversiontable in which the maximum buffer value smaller than that in the secondconversion table is defined is set to be assigned to an LCG to which alogical channel used in a transmission service in which generation ofuplink data having a volume increasing with the super high speed andlarge capacity transmission service such as eMBB is not supposed, it ispossible to suppress roughness of the granularity of the buffer valuesnotified by a buffer status report (BSR). Thus, the wireless terminal 10according to Example 3 may send the buffer value of the wirelessterminal 10 to the wireless base station 20 with higher accuracy. Inother words, the wireless base station 20 according to Example 3 mayestimate the buffer value of the wireless terminal 10 based on thebuffer status report (BSR) from the wireless terminal 10, with higheraccuracy. Such an action is useful for maintaining and improvingperformance of the super high speed and large capacity transmissionservice of an uplink in the fifth-generation mobile communicationsystem.

Example 4

In a wireless communication system 1 according to Example 4, the bitlength of a BSR index used in a transmission sequence of a buffer statusreport (BSR) for a notification of the size (also referred to as thebuffer value) of uplink data which has been stored in a buffer of awireless terminal 10 and is not transmitted yet is extended to n bits(for example, 8 bits). A reserve is specified in some indices (may alsobe referred to as BSR indices) in the BSR index table. Thus, it ispossible to suppress an occurrence of a situation in which the buffervalue of the wireless terminal 10 exceeds the maximum buffer valuedefined in the conversion table and to perform a design in which rangesof the buffer value, which are defined in the BSR index table so as tobe specified with a proper granularity.

Firstly, the motive for introduction of Example 4 will be described. Asdescribed above, the discussion in the fifth-generation mobilecommunication system is just started, and thus detailed specificationsare not fixed in many cases. Among the specifications, regarding amethod of determining a buffer value defined in the BSR index table, anidea has been proposed that inheriting the same method as for that inthe fourth-generation mobile communication system (may also be referredto as LTE).

In the fourth-generation mobile communication system, the upper limitvalue B_(k) of a buffer correlated with the k-th index defined in theBSR index table is represented by an expression as follows. The lowerlimit value of the buffer correlated with the k-th index is representedby B_(min) or B_(k-1).B _(k) =eB _(min)×(1−p)^(k) u  (1)

Here, the value p is defined by the following expression.p=(B _(max) /B _(min))^(1/(N-1))−1  (2)

In the expressions (1) and (2), the value B_(min) is the minimum value(may also be referred to as the minimum buffer value) of the bufferdefined in the BSR index table and is, for example, 10 bytes. In theexpressions (1) and (2), the value B_(max) is the maximum value (mayalso be referred to as the maximum buffer value) of the buffer definedin the BSR index table. The value N in the expression (2) is a valuedepending on the bit length of the BSR index defined in the BSR indextable. For example, in a case of a BSR index having a bit length of 6bits, the value N is 2{circumflex over ( )}6−1=63. The method ofdetermining the buffer value defined in the above-described BSR indextable is specifically described in NPL “R2-083101, Buffer Size Levelsfor BSR in E-UTRA Uplink”.

FIG. 14 illustrates a content example of a BSR index table in a casewhere the BSR index is extended to 8 bits. In the example in FIG. 14,the BSR index is extended to 8 bits, and thus 256 BSR indices havingvalues of 0 to 255 are provided. In the BSR index table in FIG. 14,buffer values determined by a method similar to that in thefourth-generation mobile communication system are defined for the 256BSR indices.

As understood from the example in FIG. 14, if the BSR index is extendedand the buffer values are defined by the method similar to that in thefourth-generation mobile communication system, a problem may occur inthat overlapping buffer values are defined in some BSR indices. That is,in the example in FIG. 14, a buffer value of “13<BS<=13” is defined fora BSR index of “5”. In other words, a buffer value which overlaps abuffer value for a BSR index of “4” is defined for the BSR index of “5”.Therefore, the BSR index of “5” comes to an index having no meaning.Alternatively, in another view, since the BS value satisfying“13<BS<=13” does not exist mathematically, the BSR index of “5” is aninvalid index. As described above, if the bit length of the BSR index isextended, it is possible to increase the maximum buffer value defined inthe BSR index table, but a problem may occur in that the granularity ofbuffer values becomes too fine. In the example in FIG. 14, the valueB_(min) is 10 bytes, and the value B_(max) is 96000000 bytes (“150Kbytes*10*16*4”=“(B_(max) in LTE)*(rate of 10 times)*16 carriers*4 ULMIMO layers”).

In Example 4, some BSR indices among a plurality of BSR indices definedin the BSR index table are handled as reserves.

FIG. 15 is a diagram illustrating a content example of the BSR indextable according to Example 4. In the BSR index table in FIG. 15, 16 BSRindices of “240” to “255” among BSR indices defined in the BSR indextable are defined as reserves. In other words, buffer values are definedfor 240 BSR indices of “0” to “239” among BSR indices having a bitlength of 8 bits. Thus, the value N in the above-described expression(2) is changed. Therefore, in the example in FIG. 15, the problem of thebuffer value for the BSR index of “15”, which has occurred in theexample in FIG. 14 is solved. In the example in FIG. 15, the first indexvalue may be “239”.

Modification Example 1

In Examples 1 to 3 described above, an example in which one first fieldand one second field are assigned for one LCG in a case where the buffervalue of the wireless terminal 10 exceeds the maximum buffer value isdescribed. However, the disclosure is not limited to the example. Forexample, one first field and a plurality of second fields may beassigned for one LCG, in accordance with the degree of the buffer valueof the wireless terminal 10 exceeding the maximum buffer value definedin the BSR index table.

For example, in S104, the wireless terminal 10 may determine whether aBSR index (may also be referred to as a first additional BSR index)obtained by converting an excess buffer value BS2 (may also be referredto as a first excess buffer value BS2 [1]) in accordance with the BSRindex table corresponds to the first index value. In a case where thefirst additional BSR index corresponds to the first index value, thewireless terminal may assign a second field (may also be referred to assecond field [1]) for storing the first additional BSR index to an LCGas the processing target. The wireless terminal 10 may acquire a secondexcess buffer value BS2 [2] by subtracting the maximum buffer value fromthe first excess buffer value BS2 [1]. Then, the wireless terminal mayassign second field [2] for storing a BSR index (second additional BSRindex) obtained by converting the second excess buffer value BS [2], toan LCG as the processing target. The wireless terminal 10 may repeatprocessing of adding a second field, in accordance with whether or notthe second additional BSR index corresponds to the first index value.

Modification Example 2

In Example 3 described above, a case where a new second field is addedto a buffer status report (BSR) for a notification of the size (alsoreferred to as a buffer value) of uplink data which has been stored inthe buffer of the wireless terminal 10 and is not transmitted yet, inaccordance with the buffer value of the wireless terminal 10 in additionto the first field for storing a BSR index value is described. However,Example 3 is not limited to this case.

For example, the wireless terminal 10 may perform the process (S101B) ofconverting the current buffer value BS into a BSR index and the process(S102) of storing the BSR index in the first field of a BSR, inaccordance with the conversion table depending on an LCG as theprocessing target, and may omit the subsequent processes (S103 to S105).

The wireless base station 20 may perform the process (S201) of acquiringa BSR index from the first field of the buffer status report (BSR) whichhas been received from the wireless terminal 10 and perform the process(S202B) of converting the BSR index acquired in S201 into a buffer valueBS1 in accordance with the conversion table depending on an LCG as theprocessing target. The wireless base station may omit the subsequentprocesses (S203 to S206).

According to an aspect of Modification Example 2, it is possible to setthe maximum buffer value in the conversion table (may also be referredto as the BSR index table), for each logical channel group (LCG) of anuplink. For example, by setting the second conversion table in which thelarge maximum buffer value is defined among a plurality of conversiontables is set to be assigned to an LCG with which a logical channel isassociated for a super high speed and large capacity transmissionservice such as eMBB belongs, it is possible to suppress an occurrenceof a situation in which the buffer value of the wireless terminal 10exceeds the maximum buffer value defined in the conversion table. Bysetting the first conversion table in which the maximum buffer valuesmaller than that in the second conversion table is defined to beassigned to an LCG with which a logical channel is associated for atransmission service in which generation of the amount of uplink data issupposed to be not as large as that in the super high speed and largecapacity transmission service such as eMBB, it is possible to suppressroughness of the step size between the buffer values of which anotification is performed by a buffer status report (BSR). Thus, thewireless terminal 10 according to Example 3 may send the buffer value ofthe wireless terminal 10 to the wireless base station 20 with higheraccuracy. In other words, the wireless base station 20 according toExample 3 may estimate the buffer value of the wireless terminal 10based on the buffer status report (BSR) from the wireless terminal 10,with higher accuracy. Such an action is useful for maintaining andimproving performance of the super high speed and large capacitytransmission service of an uplink in the fifth-generation mobilecommunication system.

Modification Example 3

In the above-described Example 4, an example of n=8 is described as anexample in which the BSR index is extended to n bits. However, Example 4is not limited thereto. For example, n is any value so long as n isgreater than 6 bits in the related art. In other words, in Example 4,some BSR indices among BSR indices of n bits (n is a value greater than6) are defined as reserves regardless of that a specific buffer value iscorrelated with the BSR index.

Modification Example 4

In the above-described Example 4, an example in which 16 BSR indices of“240” to “255” are set to be reserved is described as an example inwhich some BSR indices are set to be reserved. However, Example 4 is notlimited to this example. For example, among BSR indices having a bitlength which has been extended to n bits (n is greater than 6), i bitsmay be set as reservation bits, and buffer values may be defined for BSRindices of (n−i) bits. For example, among BSR indices having a bitlength extended to 8 bits, the one leading bit may be set as areservation bit, and buffer values may be defined for BSR indices of theremaining 7 bits. In this case, buffer values may be defined for 128 BSRindices of “0” to “127”.

Modification Example 5

In the above-described Example 4, an example in which 16 BSR indices of“240” to “255” are set to be reserved is described as an example inwhich some BSR indices are set to be reserved. However, Example 4 is notlimited to this example. For example, BSR indices of “240” to “255” aredefined to be reserved. However, 16 BSR indices of “0” to “15” may bedefined to be reserved. In this case, the BSR index of “16” is “0” andthe subsequent BSR indices have values similar to those in FIG. 15.

Modification Example 6

In the above-described Example 4, the solution for an example in whichthe buffer value of “13<BS<=13” is defined for the BSR index of “5” isdescribed. However, Example 4 is not limited thereto. As a measure forsolving a problem in that the step size becomes too fine by extendingthe bit length of the BSR index, for example, the unit of the buffervalue defined in the BSR index table may be changed. For example, theunit of the buffer value (BS value: Buffer Size Value) may be defined tobe a bit unit instead of byte. In other words, the value of the BS valuemay be multiplied by 8. With this method, a buffer size value (BSV) fora BSR index of “5” is a mathematically-valid value. Therefore, thewireless terminal may utilize a BSR using a BSV for the BSR index of“5”.

<Hardware Configuration>

Lastly, a hardware configuration of the device used in each of theexamples described above will be simply described. FIG. 16 is a diagramillustrating an example of a hardware configuration of the wirelessterminal 10 and the wireless base station 20 in the wirelesscommunication system 1.

The wireless terminal 10 illustrated in FIG. 16 includes a wirelesscommunication circuit 101, a processing circuit 102, and a memory 103.In the wireless terminal 10 illustrated in FIG. 16, illustrations ofsome components such as an antenna are omitted. The wireless terminal 10may include, for example, a display device such as a liquid crystaldisplay, an input device such as a touch panel, and a battery such as alithium-ion rechargeable battery.

The wireless communication circuit 101 is configured to receive a supplyof a baseband signal (may also be referred to as a wireless signal or adigital wireless signal) from the processing circuit 102, to generate awireless signal (may also be referred to as a second wireless signal oran analog wireless signal) having a predetermined output level from thebaseband signal, and to emit the wireless signal to the space throughthe antenna. Thus, the wireless terminal 10 may transmit a wirelesssignal to the wireless base station 20. The wireless communicationcircuit 101 is configured to receive a wireless signal input from theantenna, to convert the wireless signal into a baseband signal, and tosupply the baseband signal to the processing circuit 102. Thus, thewireless terminal 10 may receive a wireless signal from the wirelessbase station 20. As described above, the wireless communication circuit101 is configured to be capable of transmitting and receiving a wirelesssignal, and has a function of performing wireless communication with thewireless base station 20.

The wireless communication circuit 101 may be connected to theprocessing circuit 102 so as to be capable of a communication through atransmission circuit in the wireless terminal. Examples of thetransmission circuit include transmission circuits based on thestandards such as M-PHY or Dig-RF.

The processing circuit 102 (may also be referred to as a processorcircuit or an arithmetic circuit) is a circuit configured to performbaseband signal processing. The processing circuit 102 is configured togenerate a baseband signal (may also be referred to as a wireless signalor a digital wireless signal) based on a protocol stack and to outputthe baseband signal to the wireless communication circuit 101, in thewireless communication system 1. The processing circuit 102 isconfigured to perform signal processing such as demodulation or decodingon the baseband signal input from the wireless communication circuit101, based on the protocol stack in the wireless communication system 1.In other words, in an uplink, the processing circuit 102 has a functionas a circuit that transmits a wireless signal to the wirelesscommunication circuit 101 based on second data obtained by sequentiallyprocessing transmission data (may be referred to as first data which isto be transmitted), in accordance with procedure of the protocol stackin which the function of wireless communication is divided into aplurality of layers. The processing circuit 102 has a function as acircuit that sequentially processes a wireless signal received throughthe wireless communication circuit 101, from the lower layer to thehigher layer in accordance with the procedure of the protocol stack inwhich the function of wireless communication is divided into a pluralityof layers. Here, receiving an input of a baseband signal from thewireless communication circuit 101 has the meaning of receiving awireless signal from the wireless base station 20 through the wirelesscommunication circuit 101.

The processing circuit 102 may be, for example, an arithmetic devicethat reads and executes a program stored in the memory 103 so as torealize an operation of the wireless terminal 10 according to each ofthe above-described examples. In other words, the processing circuit 102has a function as a subject that performs the flow of the processing inthe wireless terminal 10 illustrated in FIGS. 4, 8, and 11. Examples ofthe processing circuit 102 include a central processing unit (CPU), amicro processing unit (MPU), a digital signal processor (DSP), a fieldprogrammable gate array (FPGA), and combinations thereof. The processingcircuit 102 may be a multicore processor including two cores or more.Regarding the processing circuit 102, two or more processing circuits102 may be mounted in accordance with each layer in the protocol stackin the wireless communication system 1. For example, a processingcircuit 102 that performs processing as a first sublayer entity (PDCPentity) belonging to a first sublayer (PDCP layer), a processing circuit102 that performs processing as a second sublayer entity (RLC entity)belonging to a second sublayer (RLC layer), and a processing circuit 102that performs processing as a third sublayer entity (MAC entity)belonging to a third sublayer (MAC layer) may be independently mounted.

The processing circuit 102 may be referred to as a C-CPU. In thewireless terminal 10, a processor circuit which is also referred to asan A-CPU that execute an application may be mounted in addition to theprocessing circuit 102. The processing circuit 102 may be mounted in aform of one chip along with a processor circuit which is also referredto as an A-CPU, or may be mounted in a form of an individual chip. Asdescribed above, the processing circuit 102 has a function as a controlunit having a function of controlling the operation of the wirelessterminal 10.

The memory 103 is a circuit configured to store and hold data orprograms relating to baseband signal processing performed by theprocessing circuit 102. The memory 103 is configured to include both orat least one of a non-volatile storage device and a volatile storagedevice. For example, a random access memory (RAM), a read-only memory(ROM), a solid state drive (SSD), a hard disk drive (HDD), and the likeare exemplified. In FIG. 16, the memory 103 is a generic name of variousstorage device such as a main storage device and an auxiliary storagedevice. Similar to the processing circuit 102, regarding the memory 103,two memories 103 or more may be mounted in accordance with each layer inthe protocol stack in the wireless communication system 1. For example,a memory 103 used in processing as the first sublayer entity (PDCPentity) belonging to the first sublayer (PDCP layer), a memory 103 usedin processing as the second sublayer entity (RLC entity) belonging tothe second sublayer (RLC layer), and a memory 103 used in processing asthe third sublayer entity (MAC entity) belonging to the third sublayer(MAC layer) may be independently mounted.

The wireless base station 20 illustrated in FIG. 16 includes a wirelesscommunication circuit 201, a processing circuit 202, a memory 203, and awired communication circuit 204. In the wireless base station 20illustrated in FIG. 16, the illustration of an antenna is omitted.

The wireless communication circuit 201 is configured to receive abaseband signal from the processing circuit 202, to generate a wirelesssignal having a predetermined output level from the baseband signal, andto emit the wireless signal to the space through the antenna, in adownlink. The wireless communication circuit 201 is configured toreceive a wireless signal input from the antenna, to convert thewireless signal into a baseband signal, and to supply the basebandsignal to the processing circuit 202, in an uplink. The wirelesscommunication circuit 201 may be connected to the processing circuit 202to be capable of a communication via a transmission path such as acommon public radio interface (CPRI). The wireless communication circuitmay also be referred to as a remote radio head (RRH) or remote radioequipment (RRE). The combination of the wireless communication circuit201 and the processing circuit 202 is not limited to one-to-onerelation. For example, a plurality of processing circuits 202 may becorrelated with one wireless communication circuit 201, a plurality ofwireless communication circuits 201 may be correlated with oneprocessing circuit 202, or a plurality of wireless communicationcircuits 201 may be correlated with a plurality of processing circuits202. As described above, the wireless communication circuit 201 has afunction as a communication unit (also referred to as a transmission andreception unit or a second transmission and reception unit) having afunction of performing a wireless communication with the wirelessterminal 10.

The processing circuit 202 is a circuit configured to perform basebandsignal processing. The processing circuit 202 is configured to generatea baseband signal based on the protocol stack in the wirelesscommunication system, and to output the baseband signal to the wirelesscommunication circuit 201, in a downlink. The processing circuit 202 isconfigured to perform receiving processing such as demodulation ordecoding, on a baseband signal input from the wireless communicationcircuit 201 based on the protocol stack in the wireless communicationsystem, in an uplink. In other words, in a downlink, the processingcircuit 202 has a function as a circuit that sequentially processestransmission data which is to be transmitted to the wireless terminal 10as a receiving device from the higher layer to the lower layer inaccordance with the procedures of the protocol stack in which thefunction of wireless communication is divided into a plurality oflayers, and transmits data obtained by the processing through thewireless communication circuit 201. The processing circuit 202 has afunction as a circuit that sequentially processes a wireless signalreceived through the wireless communication circuit 201, from the lowerlayer to the higher layer in accordance with the protocol stack in whichthe function of wireless communication is divided into a plurality oflayers, in an uplink. Here, receiving an input of a baseband signal fromthe wireless communication circuit 201 means receiving a wireless signalfrom the wireless terminal 10 through the wireless communication circuit201, in an uplink.

The processing circuit 202 may be, for example, an arithmetic devicethat reads and executes a program stored in the memory 203 so as torealize an operation of the wireless base station 20 according to eachof the above-described examples. In other words, the processing circuit202 has a function as a subject that performs the flow of the processingin the wireless base station 20 illustrated in FIGS. 5, 9, and 13.Examples of the processing circuit 202 include a central processing unit(CPU), a micro processing unit (MPU), a digital signal processor (DSP),a field programmable gate array (FPGA), and combinations thereof. Theprocessing circuit 202 may be a multicore processor including two coresor more. Regarding the processing circuit 202, two or more processingcircuits 202 may be mounted in accordance with each layer in theprotocol stack in the wireless communication system. For example, aprocessing circuit 202 that performs processing as a MAC entitybelonging to a MAC layer, a processing circuit 202 that performsprocessing as an RLC entity belonging to an RLC layer, and a processingcircuit 202 that performs processing as a PDCP entity belonging to aPDCP layer may be independently mounted. As described above, theprocessing circuit 202 has a function as a control unit (may also bereferred to as a second control unit in order to be distinguished fromthe control unit of the wireless terminal 10) having a function ofcontrolling the operation of the wireless base station 20.

The memory 203 is a circuit configured to store and hold data orprograms relating to baseband signal processing performed by theprocessing circuit 202. The memory 203 is configured to include both orat least one of a non-volatile storage device and a volatile storagedevice. For example, a random access memory (RAM), a read-only memory(ROM), a solid state drive (SSD), a hard disk drive (HDD), and the likeare exemplified. In FIG. 14, the memory 203 is a generic name of variousstorage devices such as a main storage device and an auxiliary storagedevice. Similar to the processing circuit 202, regarding the memory 203,two memories 203 or more may be mounted in accordance with each layer inthe protocol stack in the wireless communication system. For example, amemory 203 that performs processing as a MAC entity belonging to a MAClayer, a memory 203 that performs processing as an RLC entity belongingto an RLC layer, and a memory 203 that performs processing as a PDCPentity belonging to a PDCP layer may be independently mounted.

The wired communication circuit 204 performs conversion into packet datahaving a format allowed to be output to other devices and transmits thepacket data to other devices, or extracts data and the like from packetdata received from other devices and outputs the extracted data to thememory 203, the processing circuit 202, and the like. Examples of theother devices may include other wireless base stations, mobilitymanagement entities (MMEs), or serving gateways (SGWs). The MME and theSGW are also referred to as core nodes. A logical communicationinterface used in a communication with the core node is also referred toas the S1 interface. A logical communication interface used in acommunication with another wireless base station is also referred to asthe X2 interface.

The features and advantages of the disclosure will be apparent from theabove detailed description. This is intended to cover the features andadvantages of the disclosure as described above, without departing fromthe spirit and scope of the claims. In addition, any person skilled inthe related art may easily conceive of all improvements and changes.Accordingly, there is no intention to limit the scope of the inventivedisclosure to the above descriptions, and it is also possible to makesuitable improvements and equivalents falling within the scope describedin this specification. For example, the steps described in thisspecification do not have to be performed in chronological orderaccording to the sequence described as an example of the flow of theprocessing. In addition, the order of the steps may be changed, or aplurality of steps may be executed in parallel, within the scope of thegist of the present invention described in the claims. It is desirablynoted that the circumstances that may occur in the fifth-generationmobile communication system clarified in the above detailed descriptionmay be found when the fifth generation mobile communication system isexamined from one aspect, and other circumstances may be found when thefifth generation mobile communication system is examined from otheraspects. In other words, the features and advantages of the presentinvention are not limited to applications that solve the circumstancesspecified in the above detailed description.

Finally, the configurations of the examples and modifications in thedisclosure represent an example for embodying the technical idea of thepresent invention. The present invention does not intend to be limitedto the configurations of these examples and these modifications, otherembodiments included in the scope of the claims may be equally made. Forexample, it is desirably be noted that the terms in the disclosure maybe renamed when the specifications in the subsequent fifth-generationmobile communication system are set. It is also desirably noted that oneor more names aliases listed for the terms in the disclosure may bemutually synonymous.

All examples and conditional language provided herein are intended forthe pedagogical purposes of aiding the reader in understanding theinvention and the concepts contributed by the inventor to further theart, and are not to be construed as limitations to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although one or more embodiments of thepresent invention have been described in detail, it should be understoodthat the various changes, substitutions, and alterations could be madehereto without departing from the spirit and scope of the invention.

What is claimed is:
 1. A wireless terminal for a wireless communication,the wireless terminal comprising: a memory that includes a bufferconfigured to store uplink data, wherein the uplink data is configuredto be transmitted; and a controller configured to transmit a bufferstatus report, the buffer status report including an index, wherein theindex is selected from among a plurality of buffer status indices in apredetermined buffer status table by using a buffer size, the buffersize indicating a size of the uplink data stored in the buffer, whereinthe predetermined buffer status table has a predetermined content suchthat a range from a minimum value of the buffer size to a maximum valueof the buffer size is divided into a plurality of subranges, theplurality of subranges being associated with a part of the plurality ofbuffer status indices in the predetermined buffer status table, whereina rest of the plurality of buffer status indices in the predeterminedbuffer status table are associated with one or more reserved fields inthe predetermined buffer status table, wherein the minimum value of thebuffer size in the predetermined buffer status table is 0 byte, andwherein the selecting of the index is configured to select the indexfrom among the plurality of buffer status indices other than the rest ofthe plurality of buffer status indices in the predetermined bufferstatus table.
 2. The wireless terminal of claim 1, wherein a range ofthe plurality of buffer status indices is from 0 to 255, wherein therest of the plurality of buffer status indices includes at least anindex having a value of 255, wherein the buffer status report includesthe index which has a value other than
 255. 3. The wireless terminal ofclaim 2, wherein the buffer status report includes a field which storesthe index, the field being defined with a length of 8 bits.
 4. Thewireless terminal of claim 2, wherein the predetermined buffer statustable includes at least pairs defined as follows: a pair of a bufferstatus index [0] and a subrange [buffer size (BS)=0 byte]; a pair of abuffer status index [1] and a subrange [0 byte<BS≤10 bytes]; a pair of abuffer status index [2] and a subrange [10 bytes<BS≤11 bytes]; a pair ofa buffer status index [3] and a subrange [11 bytes<BS≤12 bytes]; a pairof a buffer status index [4] and a subrange [12 bytes<BS≤13 bytes]; apair of a buffer status index [5] and a subrange [13 bytes<BS≤14 bytes];a pair of a buffer status index [6] and a subrange [14 bytes<BS≤15bytes]; a pair of a buffer status index [7] and a subrange [15bytes<BS≤16 bytes]; a pair of a buffer status index [8] and a subrange[16 bytes<BS≤17 bytes]; a pair of a buffer status index [9] and asubrange [17 bytes<BS≤18 bytes]; a pair of a buffer status index [10]and a subrange [18 bytes<BS≤19 bytes]; a pair of a buffer status index[11] and a subrange [19 bytes<BS≤20 bytes]; a pair of a buffer statusindex [12] and a subrange [20 bytes<BS≤22 bytes]; a pair of a bufferstatus index [13] and a subrange [22 bytes<BS≤23 bytes]; a pair of abuffer status index [14] and a subrange [23 bytes<BS≤25 bytes]; a pairof a buffer status index [15] and a subrange [25 bytes<BS≤26 bytes]; apair of a buffer status index [16] and a subrange [26 bytes<BS≤28bytes]; a pair of a buffer status index [17] and a subrange [28bytes<BS≤30 bytes]; a pair of a buffer status index [18] and a subrange[30 bytes<BS≤32 bytes]; and a pair of a buffer status index [19] and asubrange [32 bytes<BS≤34 bytes].
 5. The wireless terminal of claim 2,wherein the selecting of the index is configured to select, based on alogical channel group of a processing target, either one of thepredetermined buffer status table or another predetermined buffer statustable, and select the index from the selected table, wherein the anotherpredetermined buffer status table has a predetermined content such thata range from another minimum value of the buffer size to another maximumvalue of the buffer size is divided into a plurality of anothersubranges, the plurality of another subranges being associated with aplurality of another buffer status indices in the another predeterminedbuffer status table, wherein the another minimum value of the buffersize in the another predetermined buffer status table is 0 bytes, andwherein the another maximum value of the buffer size in the anotherpredetermined buffer status table is less than the maximum value of thebuffer size in the predetermined buffer status table.
 6. The wirelessterminal of claim 5, wherein the another predetermined buffer statustable is assigned to a logical channel group used in a transmissionservice having large transmission capacity, and the predetermined bufferstatus table is assigned to another logical channel group used inanother transmission service having transmission capacity smaller thanthat of the transmission service.
 7. A wireless base station for awireless communication, the wireless base station comprising: a memory;and a controller coupled to the memory, the controller configured toreceive a buffer status report for a notification of a buffer sizeindicating a size of uplink data stored in a buffer, wherein thecontroller is configured to estimate the size of the uplink data basedon an index which is selected from among a plurality of buffer statusindices in a predetermined buffer status table by using a buffer sizeindicating a size of the uplink data stored in the buffer, wherein thepredetermined buffer status table has a predetermined content such thata range from a minimum value of the buffer size to a maximum value ofthe buffer size is divided into a plurality of subranges, the pluralityof subranges being associated with a part of the plurality of bufferstatus indices in the predetermined buffer status table, wherein a restof the plurality of buffer status indices in the predetermined bufferstatus table are associated with one or more reserved fields in thepredetermined buffer status table, wherein the minimum value of thebuffer size in the predetermined buffer status table is 0 byte, andwherein the selecting of the index is configured to select the indexfrom among the plurality of buffer status indices other than the rest ofthe plurality of buffer status indices in the predetermined bufferstatus table.
 8. The wireless base station of claim 7, wherein a rangeof the plurality of buffer status indices is from 0 to 255, wherein therest of the plurality of buffer status indices includes at least anindex having a value of 255, wherein the controller is configured toestimate the size of the uplink data based on the index when the bufferstatus report includes the first index which has a value other than 255.9. The wireless base station of claim 8, wherein the buffer statusreport includes a field which stores the index, the field being definedwith a length of 8 bits.
 10. The wireless base station of claim 8,wherein the predetermined buffer status table includes at least pairsdefined as follows: a pair of a buffer status index [0] and a subrange[buffer size (BS)=0 byte]; a pair of a buffer status index [1] and asubrange [0 byte<BS≤10 bytes]; a pair of a buffer status index [2] and asubrange [10 bytes<BS≤11 bytes]; a pair of a buffer status index [3] anda subrange [11 bytes<BS≤12 bytes]; a pair of a buffer status index [4]and a subrange [12 bytes<BS≤13 bytes]; a pair of a buffer status index[5] and a subrange [13 bytes<BS≤14 bytes]; a pair of a buffer statusindex [6] and a subrange [14 bytes<BS≤15 bytes]; a pair of a bufferstatus index [7] and a subrange [15 bytes<BS≤16 bytes]; a pair of abuffer status index [8] and a subrange [16 bytes<BS≤17 bytes]; a pair ofa buffer status index [9] and a subrange [17 bytes<BS≤18 bytes]; a pairof a buffer status index [10] and a subrange [18 bytes<BS≤19 bytes]; apair of a buffer status index [11] and a subrange [19 bytes<BS≤20bytes]; a pair of a buffer status index [12] and a subrange [20bytes<BS≤22 bytes]; a pair of a buffer status index [13] and a subrange[22 bytes<BS≤23 bytes]; a pair of a buffer status index [14] and asubrange [23 bytes<BS≤25 bytes]; a pair of a buffer status index [15]and a subrange [25 bytes<BS≤26 bytes]; a pair of a buffer status index[16] and a subrange [26 bytes<BS≤28 bytes]; a pair of a buffer statusindex [17] and a subrange [28 bytes<BS≤30 bytes]; a pair of a bufferstatus index [18] and a subrange [30 bytes<BS≤32 bytes]; and a pair of abuffer status index [19] and a subrange [32 bytes<BS≤34 bytes].
 11. Thewireless base station of claim 8, wherein the controller is configuredto select, based on a logical channel group of a processing target,either one of the predetermined buffer status table or anotherpredetermined buffer status table, select, based on the index obtainedfrom the buffer status report, the corresponding buffer size from theselected table, wherein the another predetermined buffer status tablehas a predetermined content such that a range from another minimum valueof the buffer size to another maximum value of the buffer size isdivided into a plurality of another subranges, the plurality of anothersubranges being associated with a plurality of another buffer statusindices in the another predetermined buffer status table, wherein theanother minimum value of the buffer size in the another predeterminedbuffer status table is 0 bytes, and wherein the another maximum value ofthe buffer size in the another predetermined buffer status table is lessthan the maximum value of the buffer size in the predetermined bufferstatus table.
 12. The wireless base station of claim 11, wherein theanother predetermined buffer status table is assigned to a logicalchannel group used in a transmission service having large transmissioncapacity, and the predetermined buffer status table is assigned toanother logical channel group used in another transmission servicehaving transmission capacity smaller than that of the transmissionservice.
 13. A transmission method of a buffer status report, the methodcomprising: acquiring an index which is selected from among a pluralityof buffer status indices in a predetermined buffer status table by usinga buffer size being a size of uplink data stored in a buffer, a part ofthe plurality of buffer status indices in the predetermined bufferstatus table being associated with a plurality of subranges divided froma range from a minimum value of the buffer size to a maximum value ofthe buffer size, and a rest of the plurality of buffer status indices inthe predetermined buffer status table associated with one or morereserved fields in the predetermined buffer status table; transmitting abuffer status report that includes the index stored in a first field,wherein the minimum value of the buffer size in the predetermined bufferstatus table is 0 byte, and wherein the selecting of the index isconfigured to select the index from among the plurality of buffer statusindices other than the rest of the plurality of buffer status indices inthe predetermined buffer status table.
 14. The transmission method ofclaim 13, wherein a range of the plurality of buffer status indices isfrom 0 to 255, wherein the rest of the plurality of buffer statusindices includes at least an index having a value of 255, wherein thebuffer status report includes an index which has a value other than 255.15. The transmission method of claim 14, wherein the buffer statusreport includes a field which stores the index, the field being definedwith a length of 8 bits.
 16. The transmission method of claim 14,wherein the predetermined buffer status table includes at least pairsdefined as follows: a pair of a buffer status index [0] and a subrange[buffer size (BS)=0 byte]; a pair of a buffer status index [1] and asubrange [0 byte<BS≤10 bytes]; a pair of a buffer status index [2] and asubrange [10 bytes<BS≤11 bytes]; a pair of a buffer status index [3] anda subrange [11 bytes<BS≤12 bytes]; a pair of a buffer status index [4]and a subrange [12 bytes<BS≤13 bytes]; a pair of a buffer status index[5] and a subrange [13 bytes<BS≤14 bytes]; a pair of a buffer statusindex [6] and a subrange [14 bytes<BS≤15 bytes]; a pair of a bufferstatus index [7] and a subrange [15 bytes<BS≤16 bytes]; a pair of abuffer status index [8] and a subrange [16 bytes<BS≤17 bytes]; a pair ofa buffer status index [9] and a subrange [17 bytes<BS≤18 bytes]; a pairof a buffer status index [10] and a subrange [18 bytes<BS≤19 bytes]; apair of a buffer status index [11] and a subrange [19 bytes<BS≤20bytes]; a pair of a buffer status index [12] and a subrange [20bytes<BS≤22 bytes]; a pair of a buffer status index [13] and a subrange[22 bytes<BS≤23 bytes]; a pair of a buffer status index [14] and asubrange [23 bytes<BS≤25 bytes]; a pair of a buffer status index [15]and a subrange [25 bytes<BS≤26 bytes]; a pair of a buffer status index[16] and a subrange [26 bytes<BS≤28 bytes]; a pair of a buffer statusindex [17] and a subrange [28 bytes<BS≤30 bytes]; a pair of a bufferstatus index [18] and a subrange [30 bytes<BS≤32 bytes]; and a pair of abuffer status index [19] and a subrange [32 bytes<BS≤34 bytes].